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4 Methods to Solve Aptitude Questions in Smart Way | Quantitative Aptitude Shortcuts | TalentSprint - YouTube
Channel: TalentSprint Aptitude Prep
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Hello friends welcome to TalentSprint
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ever wondered what successful students
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do that you don't ? what is the secret
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behind their success in this highly
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competive exams ? what is that one thing
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which can help you crack these competitive
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exams ? well the most certain answer for
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this question is the approach that you
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have for solving various questions in
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your aptitude exams .I am sure most of
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you feel that even I can answer this
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question but what is the reason that I
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am left behind well the difference
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between a winner and the others is that
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others know how to answer the question
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but winners know how to answer the
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question in a smart way so in this video
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today I am going to show you a few
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methods of answering questions or in
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smart ways let us look at what are the
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four ways of solving questions from
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aptitude and I shall explain this to you
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with the help of a few examples the
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first question here it says the
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principal amount is 20,000 time period
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is 2 years and the rate of interest is
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14% per annum
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so what is the compound interest well
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the first method of solving any question
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in aptitude is the traditional method
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the conventional method will be use the
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step by step procedure to arrive at the
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final answer but we end up wasting a lot
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of time in most of the cases like in
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this question if you go by the formula
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of compound interest which says CI
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equals to P into 1 plus R by 100 whole
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to the power of t minus P or if you take
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P common we have this formula for CI
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right P of 1 plus R by 100 whole power t
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minus 1 now all we need to do here is
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substitute the values 20,000 rate of
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interest is 14 and time period is 2 here
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so substitute the values simplify do the
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calculation and you will get the final
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answer but I am sure most of you
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understand that we will take at least
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two minutes to solve all those equations
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and arrive at the final answer so what
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is the second method of answering this
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question here well the second method
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which is different from the traditional
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method is to use your basic concepts
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your basic fundamentals of answering
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questions without
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using the conventional formula like in
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this case if you are strong in your
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basics of percentages you would
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understand that compound interest can be
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calculated using the concept of
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effective percentage which says that
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effective percentage can always be
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calculated as A plus B plus AB by 100
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where A and B are two percentages so
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compound interest is also an effective
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percentage case and hence we can say
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that the compound interest here in terms
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of percentage will be equal to A plus B
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plus AB by 100 where A is the rate of
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interest in first year and B is the rate
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of interest for the second year now
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generally the questions that we get in
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the exam have got the same rate of
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interest for both the years so in our
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case A is 40 and B also is 40 so let's
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just substitute and find out what is the
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compound interest in terms of percentage
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so A plus B plus A into B by hundred
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what do we get 14 + 14 + 14 *
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14 / 100 now 14 squared is 196 . 196 upon 100
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is 1.96 so 14 + 14 =28. 28 + 1.96
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this will come out to be 29
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.96%. so what we
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understand from this approach is that
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the compound interest in this case will
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be twenty nine point nine six percent or
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approximately 30 percentage thirty
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percent of what the principal amount
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right again if you are strong in your
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concept here you would know that the
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interest is always calculated on the
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principal amount so we can say that the
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component s in this case is 30
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percentage of twenty thousand which is
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six thousand rupees so that's how using
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the second method where we follow the
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basic fundamentals and basic concept we
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can arrive at answer much faster without
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following the traditional or the
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convention method so the answer for this
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question would be six thousand and I'm
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sure you will be able to do this in less
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than 30 seconds in your competitive exam so
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you might wonder that why did we take
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thirty percentage as the answer because
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the actual calculation says it should be
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29.96%. well
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the reason here is that in competitive
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exams most of the times the options are
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given in such a way that we can do an
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approximate calculation and arrive at
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the
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correct answer since the options are
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generally not too close to each other
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here we can assume that 29.96 is
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approximately 30 percentage right and 30
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percentage of principal amount here is
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6000 option which is closest to 6000 can
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be marked as the correct answer and
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moreover we should also understand that
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the answer has to be slightly lesser
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than 6000 so if at all we find two
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options that are close to 6000 but one
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is less than 6000 and the other being
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more than 6000 we can easily eliminate
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the wrong answer here because we know
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that answer is actual answer is 29.96
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percentage which should be less than
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6000 right so the idea here is to use
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the concept of effective percentage and
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do an approximate calculation to mark
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the answer in less than 30 seconds
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without following the Lengthy and
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time-consuming conventional method so
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this is the second method of answering
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the questions from aptitude where we use
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our basic knowledge and the concepts
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that we have discussed in answering the
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questions without using the formula or
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the conventional method let us now look
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at the third method of answering
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questions from aptitude and this is
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known as the substitution method well
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there are many types of questions where
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we can follow the method of substitution
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right this is like a reverse engineering
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all we need to do is put the option
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answers back in the question and see
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which option satisfies the given
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question here right so we simply
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substitute the answer options in the
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question one after the other and the one
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that satisfies the given question can be
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taken as a correct answer
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let's understand this with the help of
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an example now here I have a question on
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ages which says the ages of A and B are
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in the ratio of 7 : 4 after 5 years
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the ratio of their ages become 11 :
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7 what is the age of A so here simply
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two ratios have been given the first
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ratio is 7 :4 for the second ratio
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which is after 5 years becomes 11 :
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7 and we have to find out what is the
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age of the person A here and the given
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answer options are 12 years 14 years 15
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years and 28 years now most of the
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students answer even this question using
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the traditional method and end up
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spending about 45 to 60 seconds to get
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the right answer
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but if you are smart and if you use the
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substitution method you can mark the
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answer for this question in less than 10
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seconds so what do we do here try to
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substitute the answer options back in
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the question when the one point that you
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need to observe here is A: B is in
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the ratio of 7 : 4 their original
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ages are in the ratio of 7: 4
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let's look at it we can clearly
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understand that is A's age has to be a
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multiple of 7 the age of the person A
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has to be a multiple of 7 if you look at
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the answer options option A can we
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substitute this here
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no because 12 clearly is not a multiple
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of 7 so this gets ruled out let us now
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look at second option here second option
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says A's age is 14 years so substitute A
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equals to 14 now what happens if A is 14
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years it is a multiple of 7 right so the
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first condition is satisfied but the
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second conditions is after five years is
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A's age has to be a multiple of 11 now if you
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assume that 14 is the correct
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answer 14 + 5 that is A's age after 5
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years would be 19 but he is 19 a
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multiple of 11
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no so even this option gets eliminated
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so basically we are substituting 14 back
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in the question to see if it satisfies
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both the conditions or not let us now
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substitute the third option that is 15
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years is A's age is 15 years if you substitute
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15 year what happens we will say 15 by B
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equal to 7 by 4 but since most of the
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times the questions here should have the
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answer will be a integer value we know
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that 15 is not a multiple of 7 so even
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this does not seem to be the right
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answer so we can you know who rule this
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answer out and look at the last option
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of 28 years since already three of the
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answer options have been eliminated we
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can say that option 4 is the correct
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answer
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by the way if option 4 here that is 28
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years or option D 28 years let's say is
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somewhere in the first position then
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what do we do substitute back right 28
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years let's substitute A equals to 28 does
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that satisfy the first condition .Yes A's age
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has to be multiple of 7 . 28 is a multiple
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of 7 now what happens the second part of
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the question says after 5 years
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the ratio becomes 11 : 7 now A's age
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is 28 years after 5 years it would
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become 33. 28
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+ 5 is 33 is that a multiple
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of 11 yes it is so we see that the
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fourth option here or option D here
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satisfy both the conditions of the given
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question
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hence this has to be the correct answer
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so this is how in substitution method we
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just try to substitute back the answers
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in the given question and see which
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option satisfies the question are the
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conditions given in the question and let
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us now see the fourth method of
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answering questions from aptitude and
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this method is known as elimination
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method now what exactly happens here we
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don't find out the correct answer
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instead we find out what are the wrong
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answers that is to eliminate the wrong
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answer options we know that we have got
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four answered options here out of which
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one is correct and three are wrong so we
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either find out the correct answer or
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find out which three are wrong and there
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are many questions where finding out the
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three wrong answers would be much much
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easier than finding out the one correct
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answer there and these type of questions
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can be answered using elimination method
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let's understand this method with the
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help of a simple example here now this
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question from simplification says
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question mark squared plus seventy nine
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squared equals to 172 squared minus 88
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squared minus 8203 and
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we have to find out what comes in place
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of question mark again if you go by the
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traditional method we'll end up wasting
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a lot of time right
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following the conventional method will
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take at least one and half to two minutes for us
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to get the required answer if you do not
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know how to find out the squares of a
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number mentally
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however we know that will not be
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following traditional method here
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instead we'll use elimination method
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that is to eliminate the wrong answers
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from the given answer options now how do
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we do that in this question follow the
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unit digit method what we do here is
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find out what can be the unit digit of
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the given question
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and based on that we can eliminate the
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wrong answers let us do that we know
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that when a number ends in nine its
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square would end in one any number that
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ends in nine the square of that number
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would end in one because 9 squared is 81
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right 19 squared is 361 29 squared is
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841 so always when a number ends in 9
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the square ends in one
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so we know that 79 square is a number
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that ends in one it will be a four digit
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five digit number that ends in one four
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digit number that ends in one now let us
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follow a similar procedure for the
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remaining numbers as well
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172 square when a number ends in 2
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square ends in 4 likewise 88 square when
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a number ends in 8 its square also ends
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in 4 right so these are you know four
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digit numbers that end in 4 and this
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last number here is 8 2 0 3 which is a
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straightforward number that ends in 3
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here all right now let us try to do the
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simplification we have to find out what
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comes in place of question mark here
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right now the idea here is to balance
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the unit spaces on both the sides if you
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look at the right hand side there is a
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number that ends in 4 minus another
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number ending in 4 now one number ends
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in 4 the other number also ends in 4
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when we take the difference we know that
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it will end in zero for example 124
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minus 74 would end in 0 4 minus 4 gives
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us 0 so 4 minus 4 here is 0 now we have
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a number that ends in 0 minus a number
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that ends in 3 now one number ends in 0
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and the other number ends in 3 the
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result would end in don't say minus 3 if
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you know the concept here you will see
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that it ends in 7 because what do we do
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we borrow 1 from the next digit make it
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10 and 10 minus 3 will give us 7
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so clearly the right-hand side of this
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equation ends in 7 if the right-hand
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side ends in 7 it is obvious that if the
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left-hand side should also add up to 7
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now already we have a number that ends
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in 1 so what should come in placed off
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the agreed place of question mark square
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so that it is 7
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see 1 plus 6 will be equal to 7 so
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clearly question mark square should be
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ending in 6 now we know that question
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mark square ends in 6 right some number
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squared ends in 6 so what can be the huge
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space of that number it can be either 4
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or 6 right when a number ends in 6 if
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you take square root on both the sides
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what do we get
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question mark will be equal to square
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root of some number ends in 6 ending in
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6 and when a number ends in 6 its square
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root ends in either 4 or 6 so now we are pretty clear
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that the question mark should be a
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number that ends in either four or six
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let's check that from the answer options
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option a number ends in six so maybe the
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right answer look at option B ends in
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nine can this be the correct answer
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no eliminated option C ends in three
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eliminated option B also ends in three
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eliminated so we see that option B C and
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D cannot be the correct answers because
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the correct answer has to either end in
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four or six and now that we are left
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with only one choice we can say that it
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has to be in the correct answer so the
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answer for this question is 86 following
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the elimination method so this is how
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based on the question we can apply any
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of these four methods that is the
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traditional method or methods of using
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your basic concepts and fundamentals or
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the elimination method or the
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substitution method to find out the
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answer now you should follow this
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approach and understand which method
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suits for the given type of question and
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the only way to do that is practice more
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and more on various types of aptitude
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questions so I hope all of you have
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followed the four different ways of
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solving questions from aptitude now all
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you need to do is practice more and more
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and make sure that you apply the best
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method out of these four methods to
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solve the given question and arrive at
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the given answer without any difficulty
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see you in the next video thank you
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you
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