Question

There is a set of billiard (pool) balls. There are 7 striped balls, 7 solid balls, and one 8-ball. Each of the striped balls is a different color, and each of the solid balls are a different color. The 7 colors for the striped balls are the same as the colors for the solid balls. What is the probability of drawing a striped ball or a blue ball?

A 0.533

B 0.143

C 0.500

D 0.200

Answer 1

Total number of balls = 7+7+1 = 15

Number of striped balls = 7

Probability of drawing a striped ball: P(Striped) = 7/15

Number of blue balls = 2 (one for striped and one for solid balls)

Probability of drawing a solid ball: P(Solid) = 2/15

Probability of drawing a striped and blue ball: P(Striped and Blue) = 1/15

Thus, the probability of drawing a striped ball or a blue ball: P(Striped or Blue)

= P(Striped) + P(Blue) – P(Striped and Blue)

= 7/15 + 2/15 – 1/15

= 8/15

= 0.533333

≈ 0.533 [Option(A)]

[Formula used: P(A or B) = P(A) + P(B) – P(A and B)]