Question

Two rectangles are proportional in size. The larger one has a length of 21 inches and a width of 12 inches. The smaller rectangle has a width of 4 inches. What is its length?

Answer 1

Using scale factors of proportional shapes.

Sf = 12/4 = 3

Therefore the large shape is 3 times as large as the smaller shape

For length:

21/3 = 7 inches

Answer 2

Answer:

Let's assume the length/width of the left rectangle is 21 by 12.

The right rectangle's length/width will be, x(unknown length) by 4.

Find the scale factor:

Width of left

__________

Width of right

Replace values:-

 12

____ = 3, is the scale factor.

  4

Now we find the length of the small rectangle using the sf.

21/3 = 7, is the length of the smaller rectangle.