A manufacturer claims that a particular automobile will get at least 50 miles per gallon on the highway. The researchers at a consumer-oriented magazine plans to test this claim with a simple random...

A manufacturer claims that a particular automobile will get at least 50 miles per gallon on the highway. The researchers at a consumer-oriented magazine plans to test this claim with a simple random sample of 30 cars. Assuming that the standard deviation between individual cars is 2.3 miles per gallon, what should the researchers conclude if the sample
mean is 49 miles per gallon?
A. There is not sufficient evidence to reject the manufacturer’s claim; 49 miles per gallon is too close to the claimed 50 miles per gallon.
B. The manufacturer’s claim should not be rejected because the p-value of 0.0086 is too small.
C. The manufacturer’s claim should be rejected because the sample mean is less than the claimed mean.
D. The p-value of 0.0086 is sufficient evidence to reject the manufacturer’s claim.