I am really stumped by this question... I thought I got the answer but it wasn't one of the choices (multiple choice). Here is the question...

Consider the test of hypothesis to determine if the population mean is more than 50 at the 1% level of significance. The sample data for the test is: n = 64, x-bar = 46, s = 15. If the probability of a Type II error is .9664, then the value of the population mean at which this value is controlled is closest to:

A. 45.6

B. 42.2

C. 51.4

D. 48.6


I would really appreciate any help on this. Thanks a lot