Using a telephone survey a team of sociologists collect data

Using a telephone survey, a team of sociologists collect data on education and income for 154 individuals. Let xi be the highest grade completed by the ith respondent (example xi =14 means that ith respondent completed 2 years of college). Let yi be the income of the ith respondent. The sociologists have computed the following quantities after running the simple linear regression to predict the income of the individual by the highest grade completed:

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Solution