Question

A college parking lot is 140 ft long and 90 ft wide. The college wants to increase the area of the lot by 29% by adding strips of equal width to one end and one side. (So, the new shape will be a larger rectangle.) Find the width of one such strip. Round your answer to the nearest integer.

Answer 1

The initial dimenssions of the park lot are:

length: 140 ft
width: 90 ft

initial area: 140 * 90 = 12,600 ft^2

Area increased 29% = 12,600 * 1.29 = 16,254 ft^2

width of the strips: x

New length: 140 + x

New width: 90 + x

New area: (140+x)(90+x) = 16,254

Solution of the equation:

12600 + 230x + x^2 = 16254

=> x^2 + 230x - 3654 = 0

Use the quadratic formula.

x = {-230 +/- √[ 230^2 - 4*1*(-3654) ]} / 2 =

x = 14.92

The other solution is negative so it is discarded.

Answer: 15 ft