📐 Mathematics · Probability (Class 11) · JEE

A number is chosen from 1 to 20. The probability that it is divisible by 3 or 5 is:

Answer: 9/20.

Correct answer: A. 9/20

Explanation: Multiples of 3 number 6, of 5 number 4, and of 15 number 1, so by inclusion–exclusion 6 + 4 − 1 = 9, giving 9/20.

Concept context

Random experiments, sample space, events, and the axiomatic approach to probability