Question

An archery target consists of an inner circle and four concentric rings. The width of each ring is equal to the radius r of the inner circle. Enter a rational expression in terms of r that represents the probability that an arrow hitting the target at random will land in the inner circle. Then simplify the expression.

Answer 1

0.4

Explanation:

Radius of inner circle = r

Radius of entire circle = r + r + r + r + r = 5r

Probability that an arrow hitting the target will land on inner circle ;

Area of inner circle / area of entire circle

Recall :

Area of circle = πr²

Hence ;

πr² / π(5r)² = πr² / π25r² = 1 / 25 = 0.4