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V. A local newspaper has 10 delivery boys who each deliver the morning paper to

ID: 3200106 • Letter: V

Question

V. A local newspaper has 10 delivery boys who each deliver the morning paper to 50 customers every day. The owner decides to record the percentage of papers delivered on time for a 10-day period and to construct a p chart to see whether the percentage of papers delivered on time is too erratic. Based on the following table, answer the following questions:

Number of Papers Proportion of Papers

Day Delivered on Time Delivered on Time

1 458 91.6

2 447 89.4

3 464 92.8

4 450 90.0

5 432 86.4

6 484 96.8

7 457 91.4

8 494 98.8

9 476 95.2

10 468 93.6

4630 925.7

1. What is the numerical value of the center line for the p

chart?

0.926 b) 0.911 c) 0.885 d) 0.500

What is the numerical value of the lower control limit for the p chart?

a) 0.920 b) 0.81 c) 0.891 d) 0.798

What is the numerical value of the upper control limit for the p chart?

a) 0.926 b) 0.961 c) 0.979 d) 1

Which expression best characterizes the p chart?

a) Cycles b) Trend c) In-control d) Out-of-control

Explanation / Answer

from above

1)total number of papers N=5000 and proportion of paper delieved on time P =4630/5000 =0.926

hence option 0.926 is correct

2) for a day newspaers n=10*50 =500

std error =(P(1-P)/n)1/2 =0.0117

hence numerical value of the lower control limit for the p chart =0.926-3*0.0117 =0.891

therefore option C is correct

3) similarly numerical value of the upper control limit for the p chart =0.926+3*0.0117 =0.961

therefore option b is correct

4)

from above it is evident that this is out of control

therefore option D

day number(n) proportion(p) total papers(N)=(n/(p/100)) 1 458 91.60 500 2 447 89.40 500 3 464 92.80 500 4 450 90.00 500 5 432 86.40 500 6 484 96.80 500 7 457 91.40 500 8 494 98.80 500 9 476 95.20 500 10 468 93.60 500 4630 5000 0.926