A random sample of 64 students at a university showed an average age of 25 years and a sample standard deviation of 2 years. The 95% confidence interval for the true average age of all students in the university is
A) 24.6 to 25.4.
B) 24.5 to 25.5.
C) 23.0 to 27.0.
D) 20.0 to 30.0.

Question

Quizplus · Accepted Answer

Using a t-distribution with 63 degrees of freedom (n-1), and a 95% confidence level, the margin of error is 1.996. Therefore, the confidence interval is (25-1.996, 25+1.996), which simplifies to (23.004, 26.996) or (23.0, 27.0) rounded to one decimal place. The closest answer choice is B.

A Random Sample of 64 Students at a University Showed