What is the perimeter of the walkway around the pool?

• A. 180 feet
• B. 200 feet
• C. 190 feet
• D. 210 feet

Answer: (B)

When a walkway of uniform width surrounds a rectangular pool, the outer boundary grows on each side by that width. So if the pool is L feet long and W feet wide and the walkway is w feet wide, the outer dimensions become L + 2w and W + 2w. The perimeter around the walkway is the perimeter of that outer rectangle: P = 2[(L + 2w) + (W + 2w)] = 2(L + W) + 8w.

For example, if the pool is 50 feet by 30 feet and the walkway is 5 feet wide, the outer dimensions are 60 by 40, giving a perimeter of 2(60 + 40) = 200 feet. So the walkway’s perimeter is 200 feet.