Question
(a) A lot of 25 items is to be inspected by means of a two-stage sampling plan. A sample of five items is drawn. If one or more is bad, the lot is rejected. If all are nondefective, a second sample of 10 items is drawn from the remaining 20 items. The lot is then rejected if any item in the second sample is bad; otherwise it is accepted. Find the probability of accepting a lot which has two defective items. An alternative single-stage plan for this problem might be to choose a single sample of 15 items and accept the lot only if there are no defectives in the sample. Find the probability of accepting a lot of 25 with two defectives and compare this probability with that found in (a) (b)
Explanation / Answer
(a) A lot of 25 items is to be inspected by means of a two-stage sampling plan.
