Question

A flower garden is shaped like a circle. Its radius is 17 yd. A ring shaped path goes around the garden. Its outer edge is a circle with a radius 20yd. The gardener is going to cover the path with sand. If one bag of sand can cover 8yd, how many bags of sand does the gardener need? The bags must be a whole number.

Answer 1

44 bags

Explanation:

We need to find the area of the ring.

The area of the ring is the area of the outer circle minus the area of the inner circle.

outer circle: A = πr² = π × (20 yd)² = 400π yd²

inner circle: A = πr² = π × (17 yd)² = 289π yd²

area of ring: 400π yd² - 289π yd² = 111π yd²

approximate area of ring, using π = 3.14159

area of ring = 111 × 3.14159 348.72 yd²

I assume 1 bag covers 8 yd².

number of bags = 348.72 yd² / 8 yd² = 43.6 bags

Since you cannot by a fraction of a bag, we must round up.

Answer: 44 bags