Question

Find the sample variance and standard deviation of:

21, 12, 3, 9, 11


s2=?

Answer 1

42. 2

6.496

Explanation:

Given the data :

21, 12, 3, 9, 11

Variance :

S² = Σ(x - m)² ÷ (n - 1)

n = sample size = 5

m = sample mean = Σx / n

m = (21 + 12 + 3 + 9 + 11) / 5

m = 11. 2

(21-11.2)² + (12 -11.2)² + (3 - 11.2)² + (9-11.2)²

+ (11-11.2)² / (5 - 1)

S² = 42.2

Standard deviation, s = sqrt(42.2) = 6.496