An automobile dealer conducted a test to determine whether the time needed to complete a minor engine tune-up ...

     An automobile dealer   conducted a test to determine whether the time needed to complete a minor   engine tune-up depends on whether a computerized engine analyzer or an   electronic analyzer is used. Because tune-up time varies among compact,   intermediate, and full-sized cars, the three types of cars were used as   blocks in the experiment. The data (time in minutes) obtained follows. Use a=0.05 to test for any significant differences.

              Analyzer     Computerized Electronic   Car Compact 50 42   Intermediate 55 44   Full Size 63 46