Suppose that General Motors gathers from its dealers information about the percentage of new cars that require warranty work during the first year following their sale. Based on these data, GM then compares the dealerships to monitor any unusual patterns. The following table shows the number of randomly selected cars at five dealerships that required warranty work during the first year following their sale:

Warranty Work Required Dealership Yes No Aston 7 50 Dover 11 80 Springfield 7 86 Media 8 81 Newark 5 47

a. Using a = 0.05, determine if the proportion of new cars requiring warranty work differs across these dealerships.

b. Confirm your results using PHStat.

c. Interpret the meaning of the p-value from PHStat.

AppendixLO1