Question

A manufacturer of electronics will not accept a shipment of parts from a vendor if there is reason tobelieve that the mean resistance of the components is not 100 ohms. A random sample of 30 selectedfrom a large shipment yields a mean of 96 ohms and a standard deviation of 10 ohms. Should theshipment be accepted? Use a .02 level of significance and the confidence interval approach to justify your answer.

Answer 1

98% confidence interval for is

- t * S / sqrt(n) < < + t * S / sqrt(n)

96 - 2.462 * 10 / sqrt(30) <   < 96 + 2.462 * 10 / sqrt(30)

91.51 <   < 100.49

98% CI is ( 91.51 , 100.49 )

Since claimed mean resistance of component of 100 ohms is inside the confidence interval, the

shipment is accepted.