JEE Main 2021 — Statistics Question with Solution
From: JEE Main 2021 (Online) 17th March Evening Shift
Question
Consider a set of 3n numbers having variance 4. In this set, the mean of first 2n numbers is 6 and the mean of the remaining n numbers is 3. A new set is constructed by adding 1 into each of first 2n numbers, and subtracting 1 from each of the remaining n numbers. If the variance of the new set is k, then 9k is equal to __________.
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Show full solutionCorrect answer: 68
Correct answer
68
Step-by-step explanation
Let first 2n observations are x1, x2 ...................., x2n
and last n observations are y1, y2 ....................., yn
Now, ,
Now,
Now, mean is
Now, variance is
=
9k = 68
Therefore, the correct answer is 68.
and last n observations are y1, y2 ....................., yn
Now, ,
Now,
Now, mean is
Now, variance is
=
9k = 68
Therefore, the correct answer is 68.
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