CA Foundation · Quantitative Aptitude · Probability
A number is chosen at random from the integers 1 to 40. What is the probability that it is divisible by 4 or by 6?
The probability is 13/40. Among 1 to 40 there are 10 multiples of 4 and 6 multiples of 6, and 3 numbers are multiples of both. Subtracting the overlap gives 13 favourable numbers out of 40.
- A13/40Correct
- B10/40
- C16/40
- D12/40
Explanation
Multiples of 4 up to 40: 10. Multiples of 6: 6 (6 to 36). Multiples of both, i.e. of 12: 3 (12, 24, 36). Favourable = 10 + 6 - 3 = 13. Probability = 13/40. Option 16/40 simply adds 10 and 6 without subtracting the overlap.
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