A bank officer wishes to study how many customers write bad checks.To accomplish this,the officer randomly selects a weekly sample of 100 of checking accounts,and the number of who wrote bad checks was recorded.The numbers of customers who wrote bad checks in 20 consecutive weekly samples of 100 cardholders are,respectively, 1,4,9,0,4,6,0,3,8,5,3,5,2,9,4,4,3,6,4,0
Find the appropriate center line.
A).08
B).01
C).09
D).04

Question

Quizplus · Accepted Answer

The appropriate center line for an individuals control chart is the average of the sample means. Therefore, we need to find the average proportion of customers who wrote bad checks for our 20 samples:

(1/100 + 4/100 + 9/100 + 0/100 + 4/100 + 6/100 + 0/100 + 3/100 + 8/100 + 5/100 + 3/100 + 5/100 + 2/100 + 9/100 + 4/100 + 4/100 + 3/100 + 6/100 + 4/100 + 0/100) / 20

= 0.135

Therefore, the appropriate center line is 0.135, which is equivalent to 0.04 rounded to two decimal places. Thus, the best choice is D.

A Bank Officer Wishes to Study How Many Customers Write