Question

A private school opened in 2005 with an initial enrollment of 85 students. The enrollment has increased by an average of 18 students each year since the school opened. A nearby public school had an enrollment of 95 in 2005, and its enrollment has increased by an average of 15 students per year.
 Interpret the point of intersection in the context of the problem.

Answer 1

1. Let t = time in years, with t = 0 representing the year 2005. Let f(t) = the number of students enrolled at the private school and g(t) = the number of students enrolled at the public school. Create the two functions to represent the situation.

f(t) = 85 + 18t ⇒ y = 85 + 18x
g(t) = 95 + 15t ⇒ y = 95 + 15x

y = y
85 + 18x = 95 + 15x
18x - 15x = 95 - 85
3x = 10
x = 10/3
x = 3 1/3

y = 85 +18(10/3) = 85 + 180/3 = 85 + 60 = 145
y = 95 + 15(10/3) = 95 + 150/3 = 95 + 50 = 145

x = 10/3 or 3 1/3
y = 145