Question

Assume that the heights of female executives are normally distributed. A random sample of 20 female executives have a mean height of 62.5 inches and a standard deviation of 1.7 inches. Construct a​ 98% confidence interval for the population​ variance, sigma squared. Round to the nearest thousandth.

Answer 1

Given that,

Sample size,

n = 20

Sample mean,

= 62.5

Standrad deviation,

s = 1.7

Degrees of freedom = df = n - 1 = 20 - 1 = 19

= 1 - 0.98 = 0.02

/ 2 = 0.02 / 2 = 0.01

1 - / 2 = 1 - 0.01 = 0.99