Question

a) For c = 0. draw a sketch of three QC-curves on the same axes showing what the effect is of sample size (n) on the probability of acceptance for a single sampling plan. Depict three different sample sizes of n1 > n2 > n 3 .

b) What is the effect of non the probability of acceptance?

c) Design a single sampling plan for the following scenario: i. Lots with a fraction defective of 0,05 and an a of 0.05 ii. Lots with a fraction defective of 0, 15 and a probability of acceptance of 0.1

Answer 1

Formula for the three quality control curves are:

1) Operating characteristic curve:

Pa=P(d?c)= where n is sample size, d is defectives per lot, p^d is probability of defectives

this curve is between P_a and p

2) Average Outgoing quality:

AOQ=

where is n is sample size,P_a is probability of accepatance, p is proportions of defectives.

this curve is between AOQ and p

3) Average total inspection:

ATI=n+(1?Pa)(N?n).

this curve is between ATI and p

By puttiing the values in respective equations you can find the plot.