The rain wipers installed on a specific model of SUVs are from four suppliers. The proportion of wipers provided by
each supplier and the defective rate of each supplier for all four suppliers are listed in the following table. Use A, B,
C or D to denote the event that a randomly selected wiper is from Supplier A, B, C or D, respectively. Use F to
denote the event that a randomly selected wiper is defective.
Supplier Proportion Defective Rate
A 0.15 0.05
B 0.20 0.04
C 0.25 0.02
D 0.40 0.03
Total 1.00
You may use the following table to do your computations. Keep four decimal digits for your answers.
Supplier Proportion Defective Rate Joint Probabilities Revised Probabilities
A 0.15 0.05
B 0.20 0.04
C 0.25 0.02
D 0.40 0.03
Total 1.00
1. What is the probability that a randomly selected wiper is from Supplier B?
(A) 0.2308 (B) 0.2462 (C) 0.1438 (D) 0.3692 (E) none of the above
2. What is the probability that a randomly selected wiper is not from Supplier C?
(A) 0.85 (B) 0.80 (C) 0.75 (D) 0.60 (E) none of the above
3. What is the probability that a randomly selected wiper is defective?
(A) 0.0500 (B) 0.0200 (C) 0.0400 (D) 0.0325 (E) none of the above
4. Indicate if probability in the previous question is a joint, marginal, conditional or total probability.
(A) joint (B) marginal (C) conditional (D) total (E) none of the above
5. What is the probability that a randomly selected wiper is not defective?
(A) 0.9675 (B) 0.9500 (C) 0.0950 (D) 0.0968 (E) none of the above
6. Given a randomly selected wiper is defective, what is the probability that it is from Supplier B?
(A) 0.2308 (B) 0.2462 (C) 0.1538 (D) 0.3692 (E) cannot be determined
7. Indicate if the probability in the previous question is a joint, marginal, conditional or total probability.
(A) joint (B) marginal (C) conditional (D) total (E) none of the above
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8. Given a randomly selected wiper is defective, what is the probability that it is not from Supplier D?
(A) 0.7692 (B) 0.7538 (C) 0.8462 (D) 0.6308 (E) none of the above
9. Given a randomly selected wiper is defective, what is the probability that it is from Supplier C?
(A) 0.2308 (B) 0.2462 (C) 0.1538 (D) 0.3692 (E) cannot be determined
10. Given a randomly selected wiper is defective, what is the probability that it is not from Supplier A?
(A) 0.7692 (B) 0.7538 (C) 0.8462 (D) 0.6308 (E) none of the above