Question

MC Qu. 124 A methods and measurements analyst for... A methods and measurements analyst for Digital Devices needs to develop a time standard for the task of assembling a computer mouse. In a preliminary study, she observed one of her workers perform this task six times with the following results: Observation Time (Seconds) 1 1 46 2 2 3 3 38 40 4 4 5 6 34 4240 How many observations should be made if she wants to be 86.64 percent confident that the maximum error in the observed time is 5 second? Assume that the standard deviation of the task time is four seconds.

Answer 1

FORMULA:
N = ((Z * STANDARD DEVIATION) / ESTIMATE MEAN)^2

STDEV = 4
CONFIDENCE INTERVAL 86.64, WHICH GIVES A Z VALUE OF 1.5
ESTIMATED MEAN = 0.5

N = ((1.5 * 4) / (0.5)^2 = 144