Word Problem - Algebra
By Cynthia Kirkeby
Oct 25, 2004, 12:59


Topic: Word Problem

ClassBrain Visitor:

At Dan's house chores are required for his 3 sons. Every Saturday the lawn must be mowed. Marks starts moving and completes 1/3 of the lawn. Sam takes over and mows exactly 1/4 of the lawn. Jim then finished the last 700 square feet. What is the area of the yard. Would the area be x? I think you do the p=2L + 2W but I don't know where the 700 sq. ft fit in.

ClassBrain Response:

Actually you’re working with the wrong formula. You want the area not the perimeter in this problem. If they were using an edger and going around the outside of the yard, then you’d want to use the perimeter formula. In this case, you are trying to figure out the total amount of ground they are mowing.

Now, let’s see what we know.
One son (Mark) mows 1/4 or 3/12
One son (Sam) mows 1/3 or 4/12
That means that they finished:
3/12 + 4/12 = 7/12 of the yard

The last son (Jim) mows the remaining 5/12 of the yard which is equal to 700 sq. ft.

700 = 5/12

The find the total square footage of the yard, the equation becomes

700/x = 5/12

simply cross multiply and divide
5x = 8400

and you’ll see that
x = 8400/5

The total yard is 1680 sq. feet.

I hope this helps
Cynthia Kirkeby
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