A company has been receiving complaints about the attitude of some sales clerks.Over a 10-day period, the total number of complaints was 250.The company wishes to develop a control chart for the number of complaints.What would the upper control limit on the number of complaints per day be for a 2 sigma (95.5%)control chart?
A)35
B)40
C)50
D)200

Question

Quizplus · Accepted Answer

The upper control limit for a 2 sigma (95.5%) control chart is 2 standard deviations above the mean. The mean number of complaints per day is 250/10 = 25. The standard deviation is the square root of the variance, which is the mean squared deviation from the mean. The variance is (250/10 - 25)^2 = 625. The standard deviation is the square root of 625, which is 25. The upper control limit is 25 + 2(25) = 75.

A Company Has Been Receiving Complaints About the Attitude of Some