Question

The population of a certain town is growing at a constant rate. Suppose the population is 1900 initially, and after 4 years the population is 2212. Which of these expresses the rate at which the population is increasing?

Answer 1

The rate of change relates the change in population to the change in time. The population increased by 2212−1900=312 people over the four-years. To find the rate of change, divide the change in the number of people by the number of years.

2212−19004=3124

3124/4 =78

So the population increased by 78 people per year.

Because we are told that the population increased, we would expect the slope to be positive. This positive slope we calculated is therefore reasonable.