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Question 270011
JEE Mathematics · Medium

Probability: Geometric probability MCQ

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Geometric probabilityMediumQuestion 270011

Question

A number is chosen at random from 1 to 20. The probability that it is divisible by 3 or 5 is:
  1. A
    9/20
    Correct
  2. B
    6/20
  3. C
    4/20
  4. D
    10/20

Correct answer

9/20

Explanation

Divisible by 3: {3,6,9,12,15,18} = 6 numbers. Divisible by 5: {5,10,15,20} = 4 numbers. Divisible by 15: {15} = 1. By inclusion-exclusion: 6 + 4 − 1 = 9. P = 9/20.

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