Question

In a statistics course, a linear regression equation was computed to predict the final-test score from the score on the first quiz. The resulting equation was: ˆy = 25 + 0.84x with a correlation of 0.73 where y is the final test score and x is the score on the first quiz.

(a) If Carla scored 82 points on her first quiz, what is the predicted value of her score on the final test?

(b) The linear regression line predicted Frances would score an 86.74 on the test. The residual for Frances’ final prediction was -2.99. What did Frances actually score on the final test?

(c) Suppose the students’ teacher had scaled the first quiz score by adding 10 to each student’s grade. Choose the following statement(s) that are true: [Select all that apply]

i. The mean of the first quiz scores would increase by 10.

ii. The standard deviation of the first quiz scores would increase.

iii. The correlation between the first and second tests would not change.

Answer 1