JEE PYQ: Statistics Question 5
Question 5 - 2021 (18 Mar Shift 2)
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 $a^2 + b^2$ is equal to:
(1) 425 (2) 650 (3) 250 (4) 925
Show Answer
Answer: (1) 425
Solution
$\bar{x} = 0$, $\sigma_x = a$. Adding $b$: $b = 5$, $a = 20$. $a^2+b^2 = 425$.
BETA
