to illustrate the use of the oc curve let it be assumed that is 10 percent defective. a lot with 6.5 percent defectives will be accepted approximately 95 percent of the time,the frequency of acceptance inceaseing as the percent defective decreases. however,the 10 percent defective lot fails to measure up to requirement,and while it may be a marginal lot,it may not be acceptable. anexamination of the oc curve shows that a sample size of 6 will accept this marginal lot 88 percent of the time;a sample size of 84 is somewhat better,accept such a lot 65 percent of the time
if ,on the other hand, the lot is 30 percent defective, a sample size of 6 will accept the lot only 42 percent of the time,whereas a sample size of 21 will accept such a lot only 8 percent of the time and a sample size of 84 will always fail such a lot