Boxes numbered 1 to 10 are present at random. If a box is picked, find out the…

2024

Boxes numbered 1 to 10 are present at random. If a box is picked, find out the probability of selecting a box with a number which is 3 or 5’s multiple.

  1. A.

    5/2

  2. B.

    1/2

  3. C.

    8/6

  4. D.

    5/8

Attempted by 40 students.

Show answer & explanation

Correct answer: B

Correct answer: 1/2

Explanation

  1. Sample space: all box numbers from 1 to 10, so n(S) = 10.

  2. Multiples of 3 in this range: 3, 6, 9 (3 numbers).

  3. Multiples of 5 in this range: 5, 10 (2 numbers).

  4. Union of multiples of 3 or 5: 3, 5, 6, 9, 10 — total n(E) = 5.

  5. Probability = n(E)/n(S) = 5/10 = 1/2

  6. Therefore the correct probability is 1/2.

Notes on the other choices:

  • 5/2 and 8/6 are greater than 1, so they cannot be valid probabilities.

  • 5/8 is incorrect because the sample space has 10 boxes; with 5 favorable outcomes out of 10 the probability is 5/10 = 1/2.

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