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.
- A.
5/2
- B.
1/2
- C.
8/6
- D.
5/8
Attempted by 40 students.
Show answer & explanation
Correct answer: B
Correct answer: 1/2
Explanation
Sample space: all box numbers from 1 to 10, so n(S) = 10.
Multiples of 3 in this range: 3, 6, 9 (3 numbers).
Multiples of 5 in this range: 5, 10 (2 numbers).
Union of multiples of 3 or 5: 3, 5, 6, 9, 10 — total n(E) = 5.
Probability = n(E)/n(S) = 5/10 = 1/2
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.