Example 143 gives the IQ test scores of 31 seventhgrade girl

Example 14.3 gives the IQ test scores of 31 seventh-grade girls in a Midwest school district. IQ scores follow a Normal distribution with standard deviation sigma = 15. Treat these 31 girls as an SRS of all seventh-grade girls in this district. IQ scores in a broad population are supposed to have mean mu = 100. Is there evidence that the mean in this district differs from 100? Follow the four-step process, as illustrated in Example 14.9, in your answer.

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