In 1960 the United States generated 87.1 million tons of municipal solid waste and recovered (or recycled) 3.78 million tons (U.S. EPA, www.epa.gov). This means that only 4.3% of it was recovered (because 3.78/87.1 = 0.043 = 4.3%).

The amount of municipal solid waste generated in the United States can be modeled by the following formula: g = 3.14x + 87.1

The amount recovered can be modeled by the following formula: r = 0.576x + 3.78

The variable x is the number of years since 1960. For example, the year 1979 means that x=19 because 1979-1960 = 19.

The units for both g and r are in millions of tons and are represented on the vertical axis. The years since 1960 are plotted on the horizontal axis.

Use either the given equations or the given graph, as instructed, to answer the following questions.

1. a. State the value of x for the year 1972.
2. b. Find the amount of waste generated in 1972. c. Find the amount of waste recovered in 1972. d. Find the percent of waste recovered in 1972.
3. a. State the value of x for the year 1997.
4. b. Find the amount of waste generated in 1997. c. Find the amount of waste recovered in 1997. d. Find the percent of waste recovered in 1997.

Use the FORMULAS to answer questions 3 and 4. Round the answers to one decimal place.

1. a. State the value of x for the year 1986.
2. b. Find the amount of waste generated in 1986. c. Find the amount of waste recovered in 1986. d. Find the percent of waste recovered in 1986.
3. a. State the value of x for the year 2005.
4. b. Find the amount of waste generated in 2005. c. Find the amount of waste recovered in 2005. d. Find the percent of waste recovered in 2005.