Unit 2: Two-Variable Relationships

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 Practice Questions

1. Do Activity 1 on page 50-51 of Richard Scheaffer's Activity-Based Statistics book. It's available on Amazon.com.  You can "search" this book. Use the search term "correlation" and then do the activity on pg 40.  Sorry for this trouble! In previous incarnations of the course, this book was required.

If you don't plan to do this question, but are curious, the question asks you to examine several scatterplots and match the given correlation and regression equation to the scatterplots.

2. So you've just graded your class's second midterm and went through the trouble to discover that the correlation between midterm1 and midterm2 is 0.68. Oh no! You just realized that you graded a problem wrong, and that score on midterm2 should go up by 5 points. How does this affect the correlation? Explain.

3. The correlation between midterms 1 and 2 is positive. Is it possible that, on average, the class did worse on midterm 2 than on midterm 1? Explain.

4. One of your students, Rapunzel, scored half a standard deviation above average on the first midterm. The average on the second midterm was 75. Can you predict Rapunzel's score? If no, explain what additional information is required. If yes, then predict!

After giving it that old AP College Try, click here for solutions.