A Statistics Teacher Started Class One Day by Drawing the Names

Multiple Choice

A statistics teacher started class one day by drawing the names of 10 students out of a hat and asked them to do as many pushups as they could. The 10 randomly selected students averaged 15 pushups per person with a standard deviation of 9 pushups. Suppose the distribution of the population of number of pushups that can be done is approximately normal. The 95% confidence interval for the true mean number of pushups that can be done is ​

A) 5.75 to 24.25.
B) 8.56 to 21.40.
C) 11.31 to 18.55.
D) 13.02 to 16.98.