Question

what is the 95% conf. interval of a random sample of 28 and a standard deviation of 0.92 whom spends their time 2.4hrs a day

Answer 1

Solution:

Confidence interval for Population mean is given as below:

Confidence interval = Xbar ± t*S/sqrt(n)

From given data, we have

Xbar = 2.4

S = 0.92

n = 28

df = n – 1 = 27

Confidence level = 95%

Critical t value = 2.0518

(by using t-table)

Confidence interval = Xbar ± t*S/sqrt(n)

Confidence interval = 2.4 ± 2.0518*0.92/sqrt(28)

Confidence interval = 2.4 ± 0.3567

Lower limit = 2.4 - 0.3567 = 2.04

Upper limit = 2.4 + 0.3567 = 2.76

Confidence interval = (2.04, 2.76)