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sinni8
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In a series of N = 1000 items the quality control engineer
assumes the proportion pd = 2:5% of defective items.
(a) What is the expected value and the standard deviation of the number of
defective items?
(b) Assume that Nd is a number of defective items. What is the probability
distribution of Nd:?
(c) Write the normal approximation of the probability distribution of Nd:
(d) Approximate the probability of less than 15 defective items with the aid of
the normal approximation of the probability distribution of Nd: What is the
exact probability?
(e) Assume that he observed Nd = 15 defective items. What is the 95% confidence
interval for the proportion of defective items?
(f) With Nd = 40 test the hypothesis H0 : pd = 2:5% against the alternative
Hα : pd > 2:5%:
(g) Suppose he wishes to estimate the proportion of defective items with accuracy
0:5% with 99% confidence. How many items should be taken for test?
assumes the proportion pd = 2:5% of defective items.
(a) What is the expected value and the standard deviation of the number of
defective items?
(b) Assume that Nd is a number of defective items. What is the probability
distribution of Nd:?
(c) Write the normal approximation of the probability distribution of Nd:
(d) Approximate the probability of less than 15 defective items with the aid of
the normal approximation of the probability distribution of Nd: What is the
exact probability?
(e) Assume that he observed Nd = 15 defective items. What is the 95% confidence
interval for the proportion of defective items?
(f) With Nd = 40 test the hypothesis H0 : pd = 2:5% against the alternative
Hα : pd > 2:5%:
(g) Suppose he wishes to estimate the proportion of defective items with accuracy
0:5% with 99% confidence. How many items should be taken for test?