Chapter 4 Homework Problems

Answer question 1 from the following information:

Professor Jones has created a formula with which students can predict their grade on the final examination based on their total scores on the first two examinations. The prediction equation is ' = 2X + 30, where X is the total number of points the student has earned on the first two tests. The final examination has these characteristics: mean = 300 and standard deviation = 100. The correlation between total score on the first two tests and the final is .80. Kelly scored a total of 60 on the first two tests.

1. Predict Kelly's score on the final examination.

4. Assume that a test had the following characteristics: mean of X = 50; mean of Y = 500; standard deviation of X = 10; standard deviation of Y = 100; r = .80. Calculate the standard error of estimate.

5. The line of best fit for predicting Y from X is defined as ' = 10*X + 40. Jamie scored 40 on X. What is Jamie's predicted score on Y?

Answer items 7 and 8 from the following information:

The mean for VO2max is 50 ml/kg/min and the standard deviation is 10 ml/kg/min. Professor Mill wants to estimate VO2max from a field test of running a given distance for time. The coefficient of determination for the correlation between VO2max and running time is .84. Assume that his equation for predicting VO2max from running time is this: VO2max' = time in minutes (10) + 125.

7. Calculate Terry's estimated VO2max' if Terry's run time is exactly 10 minutes.

8. Calculate the error for predicting VO2max from running time.