The electronic components used to assemble a cellular phone have been exceptionally reliable, with more than 99.9% working correctly. The head of procurement believes that the current supplier meets this standard, but he tests components just the same. A test of a sample of 100 components yielded no defects. Do these data prove beyond reasonable doubt that the components continue to exceed the 99.9% target?
(a) Identify the relevant population parameter and null hypothesis.
(b) Explain why it is not appropriate to use a normal approximation for the sampling distribution of the proportion in this situation.
(c) Determine if the data supply enough evidence to reject the null hypothesis. Identify any assumptions you need for the calculation.