How Many Cycles Should Be Used in a Time Study

Multiple Choice

How many cycles should be used in a time study in order to be 95% confident that the time-study average job cycle time is within 5% of the true average job cycle time? Assume that the average job cycle time is 2.67 minutes,and the standard deviation of the sample is 0.72 minutes.

A) 36 cycles
B) 72 cycles
C) 98 cycles
D) 112 cycles