Question

A dartboard consists of five concentric circles. The radius of the smallest circle is about 1 inch. The radius of the second circle is about 3 inches longer. The radius of the third circle is about 1 inch longer than the previous circle. The radius of the fourth circle is about 2 inches longer than the previous circle. The radius of the largest circle is about 0.75 inches greater than the previous circle. What is the difference between the circumferences of the largest and smallest circle? Round your answer to the nearest tenth of an inch.

Answer 1

radius 1 = 1
radius 2 = 1+3 = 4
radius 3 = 4+1 = 5
radius 4 = 5+2 = 7
radius 5 = 7+.75 = 7.75

circumference 1 = 2π(1) = 2π
circumference 5 = 2π(7.75) = 15.5π

difference in circumference = 15.5π - 2π= 13.5π
= appr. 48.7 inches

Answer 2

42.2