CA Foundation · Quantitative Aptitude · Probability
Meera and Arjun apply independently for the same job. The probability that Meera is selected is 0.6 and the probability that Arjun is selected is 0.5. What is the probability that at least one of them is selected?
The probability that at least one is selected is 0.80. Since the events are independent, the chance that neither is selected is 0.4 × 0.5 = 0.20, and subtracting this from 1 gives 0.80.
- A0.30
- B0.70
- C0.80Correct
- D1.10
Explanation
P(neither selected) = (1 − 0.6)(1 − 0.5) = 0.4 × 0.5 = 0.20. So P(at least one) = 1 − 0.20 = 0.80. Check: 0.6 + 0.5 − 0.30 = 0.80. The value 0.70 wrongly treats the events as having a joint probability of 0.4.
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