Five years ago the population at Liberty Middle School was 1,600 students. This year the population is 1,250 students. Use the expression N-P/5 where N represents this year’s population and where P represents the previous population to find the average change in population each year.

Answer 1

To find the average change in population each year using the expression $\frac{N-P}{5}$, we first need to identify the values for $N$ and $P$:

• $N$ (this year's population) = 1,250 students
• $P$ (population five years ago) = 1,600 students

Now, we can substitute these values into the expression:

$$\frac{N-P}{5}=\frac{1,250-1,600}{5}$$

Calculating the subtraction in the numerator:

$$1,250-1,600=-350$$

Now substituting this value back into the expression:

$$\frac{-350}{5}=-70$$

Thus, the average change in population each year is $-70$ students per year. This means that, on average, the school's population has decreased by 70 students each year over the past five years.