During a Time Study,the Following Times Were Observed for a Particular

Multiple Choice

During a time study,the following times were observed for a particular job using the continuous (non-snapback) method: 22,51,72,98,128,and 150 seconds.There is only one element per cycle.The sample standard deviation of the observed times has already been computed as 3.9 seconds.If an estimate for the average time that is within 4 percent of the true long-range average 95 percent (z = 1.96) of the time is desired,how many additional observations are needed?

A) fewer than or equal to 40
B) greater than 40 but fewer than or equal to 55
C) greater than 55 but fewer than or equal to 70
D) greater than 70