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, for this test to be valid, it is necessary that the power
consumption for microwave ovens has a normal distribution.

Question

Quizplus · Accepted Answer

The validity of the test relies on the assumption that the sample mean follows a normal distribution, which is ensured if the population distribution is normal or the sample size is large enough (Central Limit Theorem).

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