420Pr1 - Practice Problem 1. Alex obtains a random sample...

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Practice Problem 1. Alex obtains a random sample of seven students from STAT 100 class he taught in Fall Semester of 2006 and wants to use it to see if there is a relationship between the number of absences and students’ final grade. The data and the scatterplot are given below. Number of Absences, x Final Grade Percentage, y 6 70 2 92 15 47 9 72 11 49 5 96 8 78 Consider the model Y i = β 0 + β 1 x i + ε i , where ε i ’s are i.i.d. N ( 0, σ 2 ). a) Find the equation of the least-squares regression line. Add the regression line to the scatter plot. b) Use the equation of the least-squares regression line obtained in part (a) to predict the final grade percentage for a student who missed 20 classes. c) Use the equation of the least-squares regression line obtained in part (a) to predict the final grade percentage for a student who missed 7 classes. d) In which prediction ( part (b) or part (c) ) would we have more confidence? Why? e) Use the equation of the least-squares regression line obtained in part (a) to find the residuals. f)*
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420Pr1 - Practice Problem 1. Alex obtains a random sample...

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