Solve the following problems by Friday January 30, 2009. Please show all work, and come to class ready to defend your solutions and reasoning.

• The average lifespan of American women has been tracked, and the model for the data is y = 0.2t + 73, where t = 0 corresponds to 1960. Explain the meaning of the slope and y-intercept.

• The equation for the speed (not the height) of a ball that is thrown straight up in the air is given by v = 128 - 32t, where v is the velocity (in feet per second) and t is the number of seconds after the ball is thrown. With what initial velocity was the ball thrown? What is the meaning of the slope?

• Fishermen in the Finger Lakes Region have been recording the deadfish they encounter while fishing in the region. The Department of Environmental Conservation monitors the pollution index for the Finger Lakes Region. The model for the number of fish deaths "y" for a given pollution index "x" is y = 9.607 + 111.958. What is the meaning of the slope? What is the meaning of the y-intercept?

• A credit manager rates each applicant for a car loan in a scale of 1 through 5 and then determines the interest rate from the accompanying table. Find the equation of the line in slope-intercept for that goes through these points.

Credit Rating, Interest
Rate, (%)
1 , 24
2 ,20
3 ,16
4, 12
5, 8