A sample of 100 wood and 100 graphite tennis rackets are taken from the warehouse. If 5 wood and 10 graphite are defective and one racket is randomly selected from the sample, find the probability that the racket is wood or defective.
a. 0.525
b. 0.55
c. 0.075
d. There is insufficient information to answer the question
2 Answers

We must notice that the requirement for “wood or defective” excludes “wood and defective” choices!!
15 in 200 rackets are defective so the chance of choosing a defective racket is 15/200 = 0.075
The probability that the choice is wood but not defective is 95/200 = 0.475 so that the total probability of wood or defective = 0.075 + 0.475 = 0.55
Answer b is correct

Graphite Tennis Rackets