Chapter 2 Quiz - Probability

1		A box has 20 screws, three of which are known to be defective. What is the probability that the first two screws taken out of the box are both defective?
			A)	0.0158
			B)	0.15
			C)	0.0237
			D)	0.0225
			E)	none of the above
2		The probability of stock A rising is 0.3; and of stock B rising is 0.4. What is the probability that neither of the stocks rise, assuming that these two stocks are independent?
			A)	0.42
			B)	0.12
			C)	0.88
			D)	0.44
			E)	0.70
3		The probability of stock A rising is 0.3; and of stock B is 0.4. If stocks A and B are not independent, and the probability of both stocks rising is 0.09, what is the probability that neither stock rises?
			A)	0.61
			B)	0.39
			C)	0.12
			D)	0.91
			E)	0.03
4		A bag has five pearls in it, out of which one is artificial. If three pearls are taken out at random, what is the probability that the artificial pearl is one of them?
			A)	1/5
			B)	2/5
			C)	3/5
			D)	4/5
			E)	none of the above
5		Suppose that two events A and B are mutually exclusive. We know that the probability of A is 0.4 and the probability of B is 0.2. The probability that either A or B (or both) will occur is:
			A)	0.08
			B)	0.52
			C)	0.60
			D)	0
			E)	none of the above
6		If the probability of A is 0.45 and the probability of the intersection of A and B is 0.15, then the probability that B will occur given that A has occurred is:
			A)	3.00
			B)	1.00
			C)	1/3
			D)	1/9
			E)	0.675
7		If P(A) = 0.2; P(B) = 0.6; and A and B are independent events, then the P(A U B) is:
			A)	P(A) + P(B)
			B)	P(A) x P(B)
			C)	P(A) + P(B) - P(A) x P(B)
			D)	zero
			E)	cannot be determined
8		If the probability of A is 0.5 and the probability of B is 0.2 and the probability of the union of A and B is 0.7, then:
			A)	A and B are independent
			B)	A and B are mutually exclusive
			C)	A and B are dependent
			D)	A and B do have an intersection
			E)	impossible to determine
9		I shoot at a target five times and each time my probability of hitting is 0.40. Assuming that each shot is independent, my probability of hitting the target at least once is:
			A)	0.01024
			B)	0.07776
			C)	0.92224
			D)	a number very close to zero
			E)	none of the above
10		The probability that I get job A is 0.45; the probability that I get job B is 0.60; and the probability that I get both the jobs is 0.30. The probability that I get at least one job offer is:
			A)	0.30
			B)	0
			C)	1
			D)	0.55
			E)	0.75
11		The probability that event A will occur is 0.7 and the probability that event B will occur is 0.7, and the probability that both events will occur is 0.49. The two events are:
			A)	independent
			B)	mutually exclusive
			C)	dependent
			D)	disjoint
			E)	insufficient information to determine
12		Five of the 12 members of the board of directors of Giganticus, Inc., will be placed on a subcommittee that will decide if John Goodhair, Chairman and CEO, will remain in his position. How many subcommittees are possible if members are randomly chosen?
			A)	792
			B)	879
			C)	972
			D)	95040
			E)	None of the above