Mary noticed that those of her friends who smoke cigarettes tend to smoke more while drinking alcohol. The table below displays the average rates of alcohol and cigarette consumption for a 1 hour period for 8 of Mary's friends

Drinks/hr Cigarettes/hr

4 5

3 4

2 4

4 7

2 3

1 2

2 4

5 7

1 draw a scatterplot

2. Compute r (2 points)

3. What type of relationship is this? Also include the strength in your response.

4. Interpret this relationship in English (hint: follow interpretation format in chapter/exercise)

5. Calculate coefficient of determination and interpret the coefficient of determination (hint: follow interpretation format in chapter/exercise)

6. Calculate the regression coefficient b and a

7. Predict the the number cigarettes smoked per hour if the person drinks 10 drinks.

8. How confident are you in making this prediction? Why? (hint: think of what r and r² is used for...)

9. Draw a regression line using the values obtained in question 7.