The manufacturer of a new hybrid sports utility vehicle (SUV)
states that it gets an average of 48 miles per gallon (mpg) on the
highway. A consumer group suspects that perhaps the new SUV’s gas
efficiency is lower than the manufacturer’s statement. Assume that
the gas efficiency of the SUV is approximately normally
distributed. The consumer group randomly tests 13 of the new SUV’s
under similar highway conditions and obtains the following results:
39, 40, 41, 42, 43, 43, 44,...