TABLE 9-3
An appliance manufacturer claims to have developed a compact microwave oven that consumes an average of no more than 250 W. From previous studies, it is believed that power consumption for microwave ovens is normally distributed with a standard deviation of 15 W. A consumer group has decided to try to discover if the claim appears true. They take a sample of 20 microwave ovens and find that they consume an average of 257.3 W.
-Referring to Table 9-3, the consumer group can conclude that there is enough evidence to prove that the manufacturer's claim is not true when allowing for a 5% probability of committing a type I error.

Question

Quizplus · Accepted Answer

The consumer group can perform a hypothesis test with the null hypothesis that the mean power consumption is 250 W. Given the sample mean of 257.3 W, a standard deviation of 15 W, and a sample size of 20, the calculated test statistic would likely exceed the critical value for a 5% significance level, indicating enough evidence to reject the null hypothesis and conclude the manufacturer's claim is not true.

TABLE 9-3 An Appliance Manufacturer Claims to Have Developed a Compact Microwave