CPM Homework Help : APCALC Problem 11-13

Multiple Choice: As a rumor spreads across a city, its rate is proportional to the product of the number of citizens who have heard the rumor and the number who have not. Which equation below could represent this scenario?

$\frac { d P } { d t }= kP(350,000 - P)$

$\frac { d P } { d x }= kx(350,000 - x)$

$\frac { d P } { d t }= kt(350,000 - t)$

$\frac { d P } { P }= k(350,000 - t)dt$

None of these

Hint:

The rumor is spreading throughout the population over time. What variables should be used?

More Help:

If $P$ represents the number of people that have heard the rumor, what is a possible expression for the number of people that have not heard the rumor?