Question 1109263: The number of streetlights in a town is growing linearly. Four months ago (n = 0) there were 130 lights. Now (n = 4) there are 146 lights. If this trend continues,
-Find an explicit formula for the number of lights in month n
-How many months will it take to reach 200 lights?
I think the difference is 4 therefore, the equation thus far is, p_(n)=p_(o)+4n.
Is P_(o) 130 since that is the starting amount? If so, then I can just substitute 200 for p_(n) to solve for the second question.
Answer by rothauserc(4718)   (Show Source):
You can put this solution on YOUR website! (146 - 130) / 4 = 4, so 4 lights are added each month
:
let y be the total number of lights for a given month
:
y = 4n + 130
:
200 = 4n + 130
:
4n = 70
:
n = 17.5 months
:
your formula is correct
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