1. A company buys batches of 10,000 printed circuit
boards from the manufacturer. They are happy to accept batches where 1.5% of the boards are faulty. If 12% of the boards are faulty they will return the boards to the manufacturer.
(a) They propose to take a sample of 25 boards to
do acceptance sampling. If 2, or less boards are faulty they will accept the batch. If more than 2 are
faulty they will not accept the batch. They will return it to the manufacturer. Find the customer' s risk and the producer's risk of the plan.
(b) An alternative plan is a 2 stage plan. In this plan,they will test 15 boards. If 0 or 1 are faulty they will accept the batch. If 3 or more are faulty they will reject the batch. If 2 or 3 are faulty they will take a second sample of 15. In this case if the
total number of defectives from both samples is less than 4 they will accept the batch , otherwise they will reject it . Find the customer's risk and the producer's risk with this sampling plan. Also calculate the expected sample size for this sampling
26 ม.ค. 50 15:42:13