Question

A 4 by 5 inch photo is enlarged by multiplying every dimension by 2 to form a similar 8 by 10 inch photo. What is the ratio of the perimeter of the smaller rectangle to that of the larger? What is the ration of the two areas?

Answer 1

Perimeter is 2l + 2w. In this case, your l can be 4 and w can be 5. So, you would do the same with the enlarged dimensions - l = 8, w = 10. Area is l*w. So, 4*5 and 8*10. Then, put the two perimeters into a fraction and the two areas into a fraction, but make sure it's either little perimeter over big perimeter and little area over big area, or else vice versa (big perimeter over little perimeter, big area over little area).