The number of streetlights in a town is growing linearly

Question

Four months a go ( n = 0) there were 130 lights. Now ( n = 4) there are 146 lights. If this trend continues, a. Find an explicit formula for the number of lights in month n b. How many months will it take to reach 200 lights?

Answer 1

Since it is linear relationship, find the slope between these two points:

 

(0, 130) and (4, 146)

 

 

Then use the point-slope form of a line to get your formula

 

y = m(x - 0) + 130

 

y = mx + 130

 

 

where m is the slope.