Question

Exhibit C:

s = 30 , n = 36 , x ¯ = 132.

Refer to Exhibit C: What is the 90% confidence interval for the population mean, μ?

Group of answer choices

Answer 1

Solution :

Given that,

Point estimate = sample mean = = 132

sample standard deviation = s = 30

sample size = n = 36

Degrees of freedom = df = n - 1 = 36 - 1 = 35

At 90% confidence level the t is ,

= 1 - 90% = 1 - 0.90 = 0.1

/ 2 = 0.1 / 2 = 0.05

t /2,df = t0.05,35 = 1.690

Margin of error = E = t/2,df * (s /n)

= 1.690 * ( 30/ 36)

Margin of error = E = 8

The 90% confidence interval estimate of the population mean is,

- E < < + E

132 - 8 < < 132 + 8

124 < < 140

(124,140) The 90% confidence interval for the population mean   = 124 , 140