Suppose the National Transportation Safety Board (NTSB) wants to examine the safety of compact cars, midsize cars, and full-size cars. It collects a sample of cars each of the cars types. The data below displays the frontal crash test performance percentages. Test whether there are statistical differences in the frontal crash test performance for each type of car.

Compact Cars	Midsize Cars	Full-Size Cars
95	95	93
98	98	97
87	98	92
99	89	92
99	94	84
94	88	87
99	93	88
98	99	89

How many pairs must be compared for follow-up t-tests?