A university wants to compare out-of-state applicants\' mean SAT math scores (1)
ID: 3153459 • Letter: A
Question
A university wants to compare out-of-state applicants' mean SAT math scores (1) to in-state applicants' mean SAT math scores (2). The university looks at 35 in-state applicants and 35 out-of-state applicants. The mean SAT math score for in-state applicants was 540, with a standard deviation of 20. The mean SAT math score for out-of-state applicants was 555, with a standard deviation of 25. It is reasonable to assume the corresponding population standard deviations are equal. To calculate the confidence interval for the difference 1 2, what is the number of degrees of freedom of the appropriate probability distribution?
64
64.87
68
69
64
64.87
68
69
Explanation / Answer
AS THE TEST INVOLVE 2 GROUPS EACH WITH N = 35
THEREFORE TOTAL POPULATION = 35+35 = 70
AS THE CONFIDENCE INTERVAL IS ABOUT THE DIFFERENCE THEREFORE THE DEGREE PF FREEDOM
= 35-1+35-1 = 68
THEREFORE OPTION C is correct
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