An appliance manufacturer claims to have developed a compact microwave oven that consumes a mean of no more than 250 W. From previousstudies, 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. What is the parameter ofinterest?

A.

257.3

B.

the mean power consumption of all such microwave ovens

C.

the mean power consumption of the 20 microwave ovens

D.

250