Discussion:
Q: The manufaturer of the new subcompact Clipper claims that it will average "40 or more miles per gallon on the open road". Some of the competitors believe this claim is too high. To investigate, an independent testing agency is hired to conduct hightway mileage tests. A random sample of 64 clippers showed their mean miles per gallon to be 38.9; with a sample standard deviation of 4.00 miels per gallon. At the significance level can the manufacturer's claim be refuted?