A random sample of 10 students was selected from the senior class at each of four large high schools, and the score of each of these 40 students on a certain mathematics examination was observed. Suppose that for the 10 students from each school, the sample mean and the sample variance of the scores were as shown in Table 11.18. Test the hypothesis that the senior classes at all four high schools would perform equally well on this examination. Discuss carefully the assumptions that you are making in carrying out this test.
Table 11.18 Data for Exercise 5 |

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