Question

Phones collected from a conferences are labeled 1 through 40. What is the probability that the conference speaker will choose a number that is not a multiple of 6?

Give your answer as a fraction.

Answer 1

Answer: 17/20

Explanation:

There are 6 multiples of 6 in the range 1 to 40, namely 6, 12, 18, 24, 30, 36. So the probability of the speaker choosing one of these multiples is 640. Therefore, by the complement rule, the probability of not choosing a multiple of 6 is 1−640=3440. Simplify to 17/20

Answer 2

15/100

Explanation:

6 multiples of 6 between 0-40 so we find the amount 40 goes into 100, which is 2.5, then multiply 6 by 2.5 to get 15, meaning the possibility is 15%, or 15/100