Perimeter of a rectangle

Question

the perimeter of a rectangle corn field is 440 meters. The ratio of its length to its width is 7:4. What is the lenght and width of the field.

Answer 1

perimeter = 2*length + 2*width (this is the equation for the perimeter of a rectangle)

The ratio of length:width is 7:4

So let the length be 7w and let the width be 4w

Now the perimeter = 2*7w + 2*4w

So 440=14w + 8w

Therefore 440=22w

Now solve for w...

But remember that when set up the problem we said that the length is 7w and the width is 4w

Now check your answer by using the equation; perimeter = 2*length + 2*width

Answer 2

Divide the perimeter by two to get exactly one length and one width (because a perimeter has two of each), which is 220.

Since the ratio is 7:4, you add 7+4 which equals 11.

Divide 220 by 11, which gives you 20.

The length is 20 times 7 (=140) and the width is 20 times 4 (= 80).

 

Check back: 140 + 80 = 220, and 2 (140 + 80) = 440, which is your perimeter.