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Octavio scores 10 points above the class mean on the midterm. How many points ab

ID: 3050117 • Letter: O

Question

Octavio scores 10 points above the class mean on the midterm. How many points above the class mean do you predict that he will score on the final? (Hint: Use the fact that the least-squares line passes through the point (x, y) and the fact that Octavio's midterm score is x + 10.) This is another example of regression to the mean: students who do well on the midterm will, in general, do less well, but still above average, on the final. (Enter your answer to one decimal place.)

points above the class mean

Explanation / Answer

Answer:

We expect that students who do well on the midterm exam in a course will usually also do well on the final exam. A professor looked at the exam scores of all 346 students who took his statistics class over a 10-year period. The least-squares line for predicting final exam score from midterm-exam score was y = 42.4 + 0.47x. (Both exams have a 100-point scale.)

Octavio scores 10 points above the class mean on the midterm. How many points above the class mean do you predict that he will score on the final? (Hint: Use the fact that the least-squares line passes through the point (x, y) and the fact that Octavio's midterm score is x + 10.) This is another example of regression to the mean: students who do well on the midterm will, in general, do less well, but still above average, on the final. (Enter your answer to one decimal place.)

4.7

points above the class mean

regression coefficient = 0.47

for 10 points , 10*0.47=4.7 points above average.

4.7

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