Question

A whole number from 1 to 15 inclusive is picked at random.

Answer 1

Answer:

• a) 3/7

• b) 3/5

Explanation:

The figure attached shows the Venn diagram for the given sets.

a) What is the probability that the number chosen is a multiple of 3 given that it is a factor of 24?

From the whole numbers 1 to 15, the multiples of 3 that are factors of 24 are in the intersection of the two sets: 3, 6, and 12.

There are a total of 7 multiples of 24, from 1 to 15.

Then, there are 3 multiples of 3 out of 7 factors of 24, and the probability that the number chosen is a multiple of 3 given that is a factor of 24 is:

• 3/7

b) What is the probability that the number chosen is a factor of 24 given that it is a multiple of 3?

The factors of 24 that are multiples of 3 are, again, 3, 6, and 12. Thus, 3 numbers.

The multiples of 3 are 3, 6, 9, 12, and 15: 5 numbers.

Then, the probability that the number chosen is a factor of 24 given that is a multiple of 3 is:

• 3/5