Question

The following information regarding the number of semester hours taken from random samples of day and evening students is provided.

x̄1 = 15.5

x̄2 = 8.1

s1 = 2.4

s2 = 2.75

n1 = 36

n2 = 65

What is the appropriate degrees of freedom for calculating a 95% confidence interval for the difference between the mean semester hours taken by the two groups of students?

Answer 1

Given:

x1 bar = 15.5 , x2 bar= 8.1 ,s1= 2.4 ,s2 = 2.75 ,n1= 36 n2= 65 and C= 0.95

We have asked to find the degrees of freedom for 95% confidence interval for the difference between the mean semester hours taken by the two groups of students.

This is pooled data, that is having equal variance.

For pooled data, we get degrees of freedom = n1 + n2 - 2

Hence the required degrees of freedom = 36 + 65 - 2 = 99

Hence  the appropriate degrees of freedom for calculating a 95% confidence interval for the difference between the mean semester hours taken by the two groups of students is 99.

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