A random sample of 250 students at a university finds that these students take a mean of $15.4$ credit hours per quarter with a standard deviation of $1.7$ credit hours. The $90 \%$ confidence interval for the mean is $15.4 \pm 0.177$. Interpret the interval.

A) We are $90 \%$ confident that the average number of credit hours per quarter of students at the university falls in the interval $15.223$ to $15.577$ hours.
B) The probability that a student takes $15.223$ to $15.577$ credit hours in a quarter is $0.90$.
C) We are $90 \%$ confident that the average number of credit hours per quarter of the sampled students falls in the interval $15.223$ to $15.577$ hours.
D) $90 \%$ of the students take between $15.223$ to $15.577$ credit hours per quarter.

Question

A random sample of 250 students at a university finds that these students take a mean of

15.4

credit hours per quarter with a standard deviation of

1.7

credit hours. The

90 \%

confidence interval for the mean is

15.4 \pm 0.177

. Interpret the interval.

A) We are $90 \%$ confident that the average number of credit hours per quarter of students at the university falls in the interval $15.223$ to $15.577$ hours.
B) The probability that a student takes $15.223$ to $15.577$ credit hours in a quarter is $0.90$.
C) We are $90 \%$ confident that the average number of credit hours per quarter of the sampled students falls in the interval $15.223$ to $15.577$ hours.
D) $90 \%$ of the students take between $15.223$ to $15.577$ credit hours per quarter.

Quizplus · Accepted Answer

The correct interpretation of a confidence interval is about the population mean, not about individual observations or the sample mean. Therefore, we are 90% confident that the true average number of credit hours per quarter for all students at the university falls within the interval 15.223 to 15.577 hours.

A Random Sample of 250 Students at a University Finds 15.415.415.4

A Random Sample of 250 Students at a University Finds $15.4$