Multiple choice

If one number is chosen at random from the first 900 positive integers, what is the probability that the number chosen is a multiple of both 3 and 5?

  1. 3/125

  2. 1/9

  3. 3/45

  4. 9/75
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Any number that is a multiple of both 3 and 5 must be a multiple of 15. The number of integers from 1 and 900 which are multiples of 15 are 15 × 1, 15 × 2, 15 × 3, ..., 15 × 60. These are 60 in number. So, the probability that one among the first 900 numbers chosen at random being a multiple of 15 is 60/900 = 6/90 = 1/15 = 3/45

Keep practicing — related questions