Question

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

Answer 1

e. 36

Step-by-step explanation:

Number of observations needed, n = (z *s / h) ^2

Where, z = number of standard deviation needed for desired confidence level of 99.74% = 3, s = Standard Deviation of task = 4 seconds, h = maximum error in the observed time = 2 seconds.

n = (3*4/ 2) ^2

n = (12/2) ^2

n = 6^2

n = 36 observations

Thus, the number of observations needed in the task is 36 observations