Question

Thomas, having mowed a large rectangular plot of grass, estimates the area to be 400 sq ft. Elva walks the perimeter of the same plot and estimates the perimeter to be 100 ft. How do you find the approximate dimensions of the plot?

Answer 1

10' X 40'.

Explanation:

If a' and b' are the dimensions, ab = 400 and 2(a+b) =100.
So, a+b =50. Eliminating b, a(50-a)=400. The roots of this quadratic are exactly 10 and 40. So, correspondingly, b = 50-a 40 and 10.