A methods and measurements analyst needs to develop a time standard for a certain task. In a preliminary study, he observed one of his workers perform this task five times, with the following results: Observation --- 1 --- 2 --- 3 --- 4 --- 5
Time(seconds) 84 ---76 - -80 --84 --76

How many observations should be made if the analyst wants to be 99.74 percent confident that the maximum error in the observed time is two seconds?

a. 25
b. 6
c. 49
d. 5
e. 36