The standard deviation of n observations x1,x2,…xn is 2 If ∑... | Mathematics | SolveeIt | Solveeit

Today, August 19

Question

The standard deviation of n observations x1,x2,…xn is 2 If ∑i=1nxi=20 and ∑i=1nxi2=100, then n is equal to

A

(A) 10 or 20

B

(B) 5 or 10

C

(C) 5 or 20

D

(D) 5 or 15

Answer

(C) 5 or 20

Explanation

Solution

Explanation:
We know SD=∑xi2n−(∑xin)22=100n−(20n)2=100n−400n2⇒4=100n−400n2