CA Foundation · Quantitative Aptitude · Probability
Meera, Karan and Sunil apply independently for a job. Their chances of being selected are 1/2, 1/3 and 1/4 respectively. What is the probability that at least one of them is selected?
The probability that at least one is selected is 3/4. Using independence, the chance that none is selected is 1/2 x 2/3 x 3/4 = 1/4, and subtracting this from 1 gives 3/4. Option 1/4 is the probability of nobody being selected.
- A3/4Correct
- B1/24
- C23/24
- D1/4
Explanation
P(none selected) = (1/2)(2/3)(3/4) = 6/24 = 1/4. So P(at least one) = 1 - 1/4 = 3/4. The option 1/4 is the probability that nobody is selected, and 1/24 is the probability that all three are selected.
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