For a Particular Time Study a Company Would Like to Be

Multiple Choice

For a particular time study a company would like to be 90% confident that the average job cycle time is within 5% of the true average job cycle time. Assume that the average job cycle time is 15.76 minutes and the standard deviation of the sample is 3.2 minutes. The number of cycles that should be used in this time study would be

A) 45.
B) 93.
C) 127.
D) 236.