A garden measuring 12 meters by 16 meters is to have a pedestrian pathway installed all around it, increasing the total area to 285 square meters. What will be the width of the pathway?
The first thing I need to do is draw a picture. Since I don't know how wide the path will be, I'll label the width as "x".
Looking at my picture, I see that the total width will be
x + 12 + x = 12 + 2x, and the total length will be
x + 16 + x = 16 + 2x.
Then the new area is given by:
diagram of garden and pathway
(12 + 2x)(16 + 2x) = 285
192 + 56x + 4x2 = 285
4x2 + 56x – 93 = 0
This quadratic is messy enough that I won't bother with trying to use factoring to solve; I'll just go straight to the Quadratic Formula:
x = [-(56) ± sqrt((56)^2 - 4(4)(-93))]/2(4) = -15.5 or 1.5
Obviously the negative value won't work in this context, so I'll ignore it. Checking the original exercise to verify what I'm being asked to find, I notice that I need to have units on my answer:
The width of the pathway will be 1.5 meters.