Match each story with a formula. Assume that the constants $P_0, r, b, A$ are all positive.

? A B C D E  1. In 1950, the population of a town was 3000 people. Over the course of the next 50 years, the town grew at a rate of 10% per decade.

? A B C D E  2. Polluted water is passed through a series of filters. Each filter removes all but 30% of the remaining impurities from the water.

? A B C D E  3. The percent of a lake's surface covered by algae, initially at 35%, was halved each year since the passage of anti-pollution laws.

? A B C D E  4. The amount of charge on a capacitor in an electric circuit decreases by 30% each second.

? A B C D E  5. In 1950, the population of a town was 3000 people. Over the course of the next 50 years, the town grew at a rate of 250 people per year.

A. $f(x) = A(2)^{-x}$

B. $f(x) = P_0(1 + r)^x$

C. $f(x) = B(0.3)^x$

D. $f(x) = B(0.7)^x$

E. $f(x) = P_0 + r x$