Question

EKU knows that on average 8.7 percent of students with a standard deviation of 3.0 will fail an EKU course. The psychology department wanted to know if their summer courses had a similar number of failing students. Dr. Lawson looked at the failing rates for the most recent summer courses (9 courses) and got the following data. Use a single-sample z-test to determine the outcome (alpha = .05, two-tailed).

Class 1: 11.0 % failed
Class 2:   8.4 % failed
Class 3: 10.2 % failed
Class 4:   9.4 % failed
Class 5:   6.8 % failed
Class 6: 13.0 % failed
Class 7:   6.8 % failed
Class 8: 9.8 % failed
Class 9: 11.9 % failed

In the box below, provide the following information:

Null Hypothesis in sentence form (1 point):
Alternative Hypothesis in sentence form (1 point):
Critical Value(s) (2 points):
Calculation WITH COHEN'S D (4 points): Note: the more detail you provide, the more partial credit that I can give you if you make a mistake.
Outcome (determination of significance or not, and what this reflects in everyday language, 2 points)

Answer 1

EKU knows that on average 8.7 percent of students with a standard deviation of 3.0 will fail an EKU course. The psychology department wanted to know if their summer courses had a similar number of failing students. Dr. Lawson looked at the failing rates for the most recent summer courses (9 courses) and got the following data. Use a single-sample z-test to determine the outcome (alpha = .05, two-tailed).

Class 1: 11.0 % failed
Class 2:   8.4 % failed
Class 3: 10.2 % failed
Class 4:   9.4 % failed
Class 5:   6.8 % failed
Class 6: 13.0 % failed
Class 7:   6.8 % failed
Class 8: 9.8 % failed
Class 9: 11.9 % failed

In the box below, provide the following information:

Null Hypothesis in sentence form (1 point):

The percentage of students fail in psychology course is 8.7

Alternative Hypothesis in sentence form (1 point):

The percentage of students fail in psychology course is different from 8.7

Critical Value(s) (2 points):

This is a two tailed test.

Critical values at 0.05 level = (-1.96, 1.96)

Rejection Region: Reject Ho is calculated z < -1.96 or z > 1.96

Calculation WITH COHEN'S D (4 points): Note: the more detail you provide, the more partial credit that I can give you if you make a mistake.

	11
	8.4
	10.2
	9.4
	6.8
	13
	6.8
	9.8
	11.9
Total	87.3

Mean = 87.3/9=9.7

z =1

COHEN'S D = (9.7-8.7)/3 = 0.33

Outcome (determination of significance or not, and what this reflects in everyday language, 2 points)

Calculated z = 1 not in the rejection region .

The null hypothesis is not rejected.

We conclude that psychology department summer courses had a similar number of failing students as EKU course.