Because of variability in the manufacturing process, the actual yielding point of a sample of mild steel subjected to increasing
stress will usually differ from the theoretical yielding point. Let p denote the true proportion of samples that yield before their theoretical yielding point. If on the basis of a sample it can be concluded that more than 20% of all specimens yield before the theoretical point, the production process will have to be modified. (a) If 9 of 40 specimens yield before the theoretical point, what is the P-value when the appropriate test is used? (Round your answer to four decimal places.) P-value
P ( A ) = 0.45 - probability that the land has oil, P ( B ) = 0.8 - probability that the test predicts it P ( A ∩ B ) = P ( A ) · P ( B ) = 0.45 · 0.8 = 0.36 Answer: The probability that the land has oil and the test predicts it is 36 %.