SCENARIO 9-3
An appliance manufacturer claims to have developed a compact microwave oven that consumes a
mean of no more than 250 W.From previous studies, it is believed that power consumption for
microwave ovens is normally distributed with a population 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 a mean of 257.3 W.
-True or False: Referring to Scenario 9-3, the null hypothesis will be rejected at 5% level of
significance.

Question

Quizplus · Accepted Answer

The null hypothesis is that the mean power consumption is 250 W. The sample mean is 257.3 W, with a standard deviation of 15 W and a sample size of 20. Using a z-test, the calculated z-value is greater than the critical z-value at a 5% significance level, leading to the rejection of the null hypothesis.

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