Sample Probability Practice Questions:

1. If P(A) = 0.5, P(B) = 0.6, and P(A f' B) = 0.3, then P(A U B) is:

(a) 0.8000.

(b) 0.5000.

(c) 0.6000.

(d) 0.0000.

2. If P(A) = 0.3, P(B) = 0.5, and P(A U B) = 0.6, then P(A/B) is:

(a) 0.5000.

(b) 0.8333.

(c) 0.4000.

(d) 0.4500. .

3. If P(A) = 0.6, P(B) = 0.3, and P(A/B) = 0.4, then P(A U B) is:

(a) 0.7800.

(b) 0.1200.

(c) 0.6667.

(d) 0.2200.

4. If A and B are independent events and P(A) = 0.3 and P(B) = 0.6, then P(A ∩B) is:

(a) 0.7200.

(b) 0.9000.

(c) 0.1800.

(d) 0.5000

5. If P(A) = 0.6, P(B) = 0.3, and P(AIB) = 0.4, then P(Ac) is:

(a) 0.4000.

(b) 0.1000.

(c) 0.6000.

(d) 0.1200.

6. The probability that any one of two engines on an aircraft will fail is 0.001. Assuming that the engines operate

independently of each other, the probability that both engines will not fail is:

(a) (0.001)2

(b) 0.002

(c) (0.001)(0.999).

(d) (0.999)2

7. In a particular rural region, 65 percent of the residents are smokers, and research indicates that 15 percent of the

smokers have some form of lung cancer. The probability of a resident's having lung cancer given that the

resident is a smoker is:

(a) 0.0975.

(b) 0.2308.

(c) 0.1500.

(d) 0.6500.

8. If P(A) = 0.5, P(B) = 0.4, and P(AIB) = 0.9, then P(B/A) is:

(a) 0.4500.

(b) 0.3600.

(c) 0.5556.

(d) 0.7200.

9. If A and B are two independent events with P(A) = 0.15 and P(B) = 0.7, then P(A ∩ B) is

(a) 0.5500.

(b) 0.2143.

(c) 0.1050.

(d) 0.8500.

10. If A and B are two independent events with P(A) = 0.15 and P(B) = 0.4, then P(A U B) is

(a) 0.5500.

(b) 0.3750.

(c) 0.0600.

(d) 0.4900.

Answers

1. (a) 2. (c) 3. (a) 4. (c) 5. (a) 6. (d) 7. (c) 8. (d) 9. (c) 10. (d)

1,3,5,7,9,19,29,35,37,39