Question

A university researcher wants to estimate the mean number of novels that seniors read during their time in college. An exit survey was conducted with a random sample of 9 seniors. The sample mean was 7 novels with standard deviation 2.29 novels. Assuming that all conditions for conducting inference have been met, what is a 95 percent confidence interval for the population mean number of novels read by all seniors?

Answer 1

(5.240 ; 8.760)

Explanation:

Given :

Sample mean, xbar = 7

Standard deviation, s = 2.29

Sample size, n = 9

95% confidence interval for the population mean :

Confidence interval :

Xbar ± Margin of error

Margin of Error = Tcritical * s/sqrt(n)

Tcritical at 0.05 ; df = 8 = 2.306

Margin of Error = 2.306 * 2.29/sqrt(9)

Margin of Error = 1.760

Lower boundary = (7 - 1.760) = 5.240

Upper boundary = (7 + 1.760) = 8.760

(5.240 ; 8.760)