Question

Students in a statistics class are conducting a survey to estimate the mean number of units students at their college are enrolled in. The students collect a random sample of 48 students. The mean of the sample is 12.4 units. The sample has a standard deviation of 1.7 units.

Required:
What is the 95% confidence interval for the average number of units that students in their college are enrolled in?

Answer 1

[11.906 ; 12.894]

Explanation:

Given :

Sample mean, xbar = 12.4

Sample standard deviation, s = 1.7

Sample size, n = 48

We use the T distribution since we are using the sample standard deviation;

α - level = 95% ; df = n - 1 = 48 - 1 = 47

Tcritical = T(1 - α/2), 47 = 2.012

Using the confidence interval for one sample mean

Xbar ± Tcritical * s/√n

12.4 ± (2.012 * 1.7/√48)

12.4 ± 0.4936922

C. I = [11.906 ; 12.894]