CA Foundation · Quantitative Aptitude · Probability
A number is chosen at random from the integers 1 to 50. What is the probability that it is a multiple of 4 or a multiple of 6?
Multiples of 4 number 12, multiples of 6 number 8, and common multiples of 12 number 4. By inclusion-exclusion the favourable count is 12 + 8 - 4 = 16, so the probability is 16/50.
- A20/50
- B18/50Correct
- C21/50
- D16/50
Explanation
Multiples of 4: 12 (4 to 48). Multiples of 6: 8 (6 to 48). Multiples of both, i.e. of 12: 4 (12, 24, 36, 48). Favourable = 12 + 8 - 4 = 16, so probability is 16/50. Check: that gives option 16/50, not 18/50.
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