Question

You have a standard number cube. What is the probability of rolling a number less than 3, and then rolling a prime number?

Answer 1

The probability is `1/6`. See explanation for details.

Explanation:

To calculate this probability you have to calculate probabilitues of both events and multiply them.

First the event rolling less than 3.

There are 2 numbers less than three and 6 numbers in total on the cube, so the probability is:

`P(A)=2/6=1/3`

Now let's take rolling a prime number:

A prime number is a natural number greater than 1 which can only be divided without a remainder by 1 and itself. So from the numbers on the cube prime numbers are: `2,3` and `5`. The probability of getting a prime number in a single roll is:

`P(B)=3/6=1/2`

Now to calculate the probability of `A` and `B` you have to multiply both probabilities:

`P(AnnB)=P(A)*P(B)=1/3*1/2=1/6`