Practice and Problem-Solving Exercises

A Practice

See Problem 1.

For each table, make a scatter plot of the data. Describe the type of correlation the scatter plot shows.

7. Jeans Sales

   Average Price ($)	21	28	36	40
   Number Sold	130	112	82	65

8. Gasoline Purchases

   Dollars Spent	10	11	9	8	13
   Gallons Bought	2.6	3	2.4	2.2	3.5

See Problem 2.

Theme Parks Use the table below for Exercises 9 and 10.

SOURCE: International Association of Amusement Parks and Attractions

9. Make a scatter plot of the data pairs (year, attendance). Draw a trend line and write its equation. Estimate the attendance at U.S. theme parks in 2005.

10. Make a scatter plot of the data pairs (year, revenue). Draw a trend line and write its equation. Predict the revenue at U.S. theme parks in 2012.

    See Problem 3.

11. Entertainment Use a graphing calculator to find the equation of the line of best fit for the data in the table. Find the value of the correlation coefficient r to three decimal places. Then predict the number of movie tickets sold in the U.S. in 2014.

    Movie Tickets Sold in U.S. by Year

    Year	1998	1999	2000	2001	2002	2003	2004	2005	2006	2007
    Tickets Sold (millions)	1289	1311	1340	1339	1406	1421	1470	1415	1472	1470

    SOURCE: Motion Picture Association of America

See Problem 4.

In each situation, tell whether a correlation is likely. If it is, tell whether the correlation reflects a causal relationship. Explain your reasoning.

12. the amount of time you study for a test and the score you receive
13. a person's height and the number of letters in the person's name
14. the shoe size and the salary of a teacher
15. the price of hamburger at a grocery store and the amount of hamburger sold

B Apply

16. Open-Ended Describe three real-world situations: one with a positive correlation, one with a negative correlation, and one with no correlation.

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