Question

The data below represent a random sample of 9 scores on a statistics quiz. (The maximum possible score on the quiz is 10.) Assume that the scores are normally distributed with a standard deviation of 2.2. Estimate the population mean with 95% confidence.

8,9,8,4,4,7,2,10,8

Note: For each confidence interval, enter your answer in the form (LCL, UCL). You must include the parentheses and the comma between the confidence limits.

Confidence Interval =

Answer 1

From given sample = X / n = 6.6667

95% confidence interval for is

- Z/2 * / sqrt(n) < < + Z/2 * / sqrt(n)

6.6667 - 1.96 * 2.2 / sqrt(9) < < 6.6667 + 1.96 * 2.2 / sqrt(9)

5.23 < < 8.10

95% CI is ( 5.23 , 8.10 )