Estimate the population mean by finding a 95% confidence interval given a sample of size 15, with a mean of 47.8 and a standard deviation of 11.2.

Question

Estimate the population mean by finding a 95% confidence interval given a sample of size 15, with a mean of 47.8 and a standard deviation of 11.2. 

Confidence Interval: What is the 95% confidence interval to estimate the population mean? Enter your answer as an open-interval (i.e., parentheses) accurate to one decimal place.

95% C.I. =

Answer 1

47.8 = mean=xbar

11.2 = standard deviation= s

15 = sample size=n

z= 1.96 for 95% CI

CI = xbar +/-zs/sqrn

=47.8+/- 1.96(11.2)/sqr15

= about 47.8 +/- 5.67

= (47.8-5.67, 47.8+5.67)

= (42.13,53.47)

= (42.1, 53.5)

or

42.1<x<53.5