Question

Ifarandom sample of 15 provides a mean of 18 and a variance of 16, what would be the 95% confidence Interval estimate for the standard deviation of the population?

O 1.72 to 8.33

O 2.93 to 6.31

O 6.71 to 32.44

O 4.21 to 15.61

O 2.72 to 7.23

O The correct answer is not listed.

O 1.85 to 7.73

O 1.58 to 39.45

O 4.75 to 12.33

Answer 1

95% confidence interval for is

From chi square table,

df = n -1 = 15 - 1 = 14

(0.05/2, 15 - 1 ) = 26.1189
(1 - 0.05/2, 15 - 1) ) = 5.6287

sqrt (( 15-1 ) * 16 / 26.1189 ) < < sqrt ((15-1) * 16 / 5.6287 )

2.93 < < 6.31

2.93 to 6.31