Multiple choice

Twenty cards, numbered 1, 2, 3 … 20, are put in a box and mixed thoroughly. A card is then drawn from the box. Find the probability that the number on the selected card is divisible by 3 and 5 both.

  1. 1 10

  2. 3 20

  3. 1 5

  4. 1 20
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D Correct answer
Explanation

Numbers divisible by both 3 and 5 must be divisible by 15. In the range 1 to 20, only 15 is divisible by 15. Thus, there is 1 favorable outcome out of 20.

AI explanation

A number from 1 to 20 divisible by both 3 and 5 must be a multiple of their least common multiple, which is 15. The only such number is 15, giving exactly 1 favorable outcome. The required probability is the ratio of favorable outcomes to total outcomes, which is 1/20.

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