Consumer Reports indicated that the mean acceleration time (0 to 60 mph)

for a certain car was 10.2 seconds. In most tests of this type, regular

gasoline is used. Suppose that 40 such tests were made using premium

gasoline and that sample mean acceleration time, x , was 9.8 seconds with a

sample standard deviation, s , of 2.1 seconds. Does this indicate that

premium gasoline reduces acceleration time, on average? Use = 0.01.