A farmer has a 40 ft by 50 ft rectangular field that he wants to reduce to 10% of its original size. How wide of a strip should he cut around the edge of his field to do this?

Answer 1

40x50=2000

10% less = 1800

(40-2x)(50-2x)=1800

2000- 180x +4x^2 = 1800

4x^2 -180x +200= 0

x^2 -45x + 50=0

x =45/2 -.5sqr(2025-200)

x=22.5 - .5sqr1825

x= about 22.5-21.36= 1.14 feet wide strip

37.72x47.72= 1800