Suppose that a supplier ships components in lots of size 5,000. A single-sampling plan with  and  is being used for receiving inspection. Rejected lots are screened, and all defective items are reworked and returned to the lot. 

a. Draw the OC curve for this plan.

b. Find the level of lot quality that will be rejected 90% of the time.

c. Management has objected to the use of the above sampling procedure and wants to use a plan with an acceptance number , arguing that this is more consistent with their Zero Defects program. What do you think of this?

d. Design a single-sampling plan with  that will give a 0.90 probability of rejection of lots having the quality level found in part (b). Note that the two plans are now matched at the LTPD point. Draw the  curve for this plan and compare it to the one for,  in part (a).

e. Suppose that incoming lots are 0.5% nonconforming. What is the probability of rejecting these lots under both plans? Calculate the ATI at this point for both plans. Which plan do you prefer? Why?

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