# Help Please!

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• Sep 24th 2006, 05:54 PM
sallyann
Help Please!
PLEASE tell me if I am way off. The answer I got for this one is 3.5 ft.

A parking lot measures 100 by 130 feet. A sidewalk of uniform width is to completely surround the lot. If the sidewalk covers 1659 sq ft. how wide can the sidewalk be?

Thanks!
• Sep 24th 2006, 06:00 PM
Quick
Quote:

Originally Posted by sallyann
PLEASE tell me if I am way off. The answer I got for this one is 3.5 ft.

A parking lot measures 100 by 130 feet. A sidewalk of uniform width is to completely surround the lot. If the sidewalk covers 1659 sq ft. how wide can the sidewalk be?

Thanks!

you have rectangle 100x130

the sidewalk plus the parking lot equals: (100+2s)x(130+2s)

the area is therefore: (100+2s)x(130+2s)=13000+260s+200s+4s^2=4s^2+460s+1 3000

now subtract the original rectangle area (100x130=13000) from the sidewalk+parking lot area to get: 4s^2+460s

that expression gives the area of the sidewalk for width "s"

now solve for: 4s^2+460s=1659

which comes out to: s=3.5

so you got it right :)