math
posted by kim on .
a rectangle is 7 ft by 9ft. a second is similar to the first with a perimeter of 260 ft. what are the dimensions of the second rectangle?

if the new one is similar to the old one, then it must be
7x by 9x
and its perimeter would be 2(7x+9x) or 32x
so 32x = 260
x = 8.125
so the new one is 7(8.125) by 9(8.125)
or
56.875 by 73.125
check : 73.125/56.875 = 73125/56875 = 2925/2275 = 9/7  ratio works
perimeter = 2(56.875) + 2(73.125) = 260  checks!