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godemol
- Junior | Next Rank: 30 Posts
- Posts: 18
- Joined: Sat Jun 20, 2009 6:06 pm
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- GMAT Score:720
Guys, a simple question, but I am having hard time grasping. Need your help:
The events A and B are independent. The probability that event A occurs is p and the probability that event B occurs is q. Which of the following is equal to the probability that exactly one of the events A and B occurs?
A. p − 2pq
B. q − pq
C. p + q − 2pq
D. p + q − pq
E. p + q
The answer is C. But, the part that I am having trouble understanding is the bold statement above: the probability that exactly one of the events A and B occurs...isn't that equivalent to "the probability that either A or B occurs? In other words, P(A or B), which would make choice D a correct answer?
The events A and B are independent. The probability that event A occurs is p and the probability that event B occurs is q. Which of the following is equal to the probability that exactly one of the events A and B occurs?
A. p − 2pq
B. q − pq
C. p + q − 2pq
D. p + q − pq
E. p + q
The answer is C. But, the part that I am having trouble understanding is the bold statement above: the probability that exactly one of the events A and B occurs...isn't that equivalent to "the probability that either A or B occurs? In other words, P(A or B), which would make choice D a correct answer?
