A random sample of 250 students at a university finds that these students take a mean of 14.3 credit hours per quarter with a standard deviation of 1.7 credit hours. The 95% confidence interval for the mean is 14.3 ± 0.211. Interpret the interval.

A) The probability that a student takes 14.089 to 14.511 credit hours in a quarter is 0.95.
B) 95% of the students take between 14.089 to 14.511 credit hours per quarter.
C) We are 95% confident that the average number of credit hours per quarter of the sampled students falls in the interval 14.089 to 14.511 hours.
D) We are 95% confident that the average number of credit hours per quarter of students at the university falls in the interval 14.089 to 14.511 hours.

Question

A random sample of 250 students at a university finds that these students take a mean of 14.3 credit hours per quarter with a standard deviation of 1.7 credit hours. The 95% confidence interval for the mean is 14.3 ± 0.211. Interpret the interval.

A) The probability that a student takes 14.089 to 14.511 credit hours in a quarter is 0.95.
B) 95% of the students take between 14.089 to 14.511 credit hours per quarter.
C) We are 95% confident that the average number of credit hours per quarter of the sampled students falls in the interval 14.089 to 14.511 hours.
D) We are 95% confident that the average number of credit hours per quarter of students at the university falls in the interval 14.089 to 14.511 hours.

Quizplus · Accepted Answer

The confidence interval is used to estimate the population mean, not the sample mean or individual values. Thus, we are 95% confident that the true average number of credit hours per quarter for all students at the university falls within this interval.

A Random Sample of 250 Students at a University Finds