What is the standard deviation (SD) of the four numbers p, q, r, s?
1. The sum of p, q, r and s is 24
2. The sum of the squares of p, q, r and s is 224
5-Day Free Trial
5-day free, full-access trial TTP
Available with Beat the GMAT members only code
MORE DETAILS
DS...SD...
This topic has expert replies
-
x2suresh
- Master | Next Rank: 500 Posts
- Posts: 258
- Joined: Thu Aug 07, 2008 5:32 am
- Thanked: 16 times
C .ontopofit wrote:What is the standard deviation (SD) of the four numbers p, q, r, s?
1. The sum of p, q, r and s is 24
2. The sum of the squares of p, q, r and s is 224
VARIANCE =SD^2 = 1/N { SUM (Squares of numbers) - Avg(numbers)^2 }
= 1/4*(224 - 36)
