JEE Main 2021 — Statistics Question with Solution
From: JEE Main 2021 (Online) 18th March Evening Shift
Question
Let in a series of 2n observations, half of them are equal to a and remaining half are equal to a. Also by adding a constant b in each of these observations, the mean and standard deviation of new set become 5 and 20, respectively. Then the value of a2 + b2 is equal to :
Choose an option
Show full solutionCorrect option: A
Correct answer
A425
Step-by-step explanation
Given series
(a, a, a, ........ n times), (a, a, a, ...... n times)
Now =
as, xi xi + b
then + b
So, + b = 5 b = 5
No change in S.D. due to change in origin
Standard deviation () =
a2 + b2 = 425
(a, a, a, ........ n times), (a, a, a, ...... n times)
Now =
as, xi xi + b
then + b
So, + b = 5 b = 5
No change in S.D. due to change in origin
Standard deviation () =
a2 + b2 = 425
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