Math 100A (Lutz) - Quiz #12
Name:
11/09/12
Directions: This quiz has 2 questions, for a total of 10 points. Solve each problem carefully. You must
show ALL of your work in order to earn full credit.
1. (6 points) In a mountainous region, the annual snowfall, in inches, is directly proportional to the
altitude above sea level, in feet. The annual snowfall at 7500 ft above sea level is 150 inches.
a What is the constant of proportionality, and what are its units?
b What is the annual snowfall at 9000 ft above sea level?
2. (4 points) In the year 1960, the average life expectancy of humans was 70 years. In each decade since
1960, the average life expectancy increases by 1.5 years. Express the average life expectancy of humans
L (in years) as a function of decades d since 1960.