Pat is making a Christmas tree skirt. She needs to know how much fabric to buy. Using the example provided, calculate the area of the skirt to the nearest foot.
a. 37.7 ft2
b. 27 ft2
c. 75 ft2
d. 38 ft2
d. To determine the area of the skirt, evaluate the area of the outer circle minus the area of the inner circle. The area of the outer circle is π (3.5)2 or 38.465 in2. The area of the inner circle is π (.5)2 or .785 in2. The difference is 38.465 - .785 or 37.68 ft2. The answer, rounded to the nearest foot, is 38 ft2. If you select a, you rounded to the nearest tenth of a foot. If you select b, you calculated the radius of the outer circle as being 3 feet instead of 3.5 feet.