Question

You roll a number cube numbered from 1 to 6. What is the probability that the number is a composite number?

Answer 1

For the six numbers in the cube, we have.

• 1 is not prime nor composite
• 2 is prime
• 3 is prime
• 4 is composite, because it can be written as
  `2\cdot 2`
• 5 is prime
• 6 is composite, because it can be writte as
  `2\cdot 3`

So, only two of the numbers in the cube are composite. This means that you have a chance of

`(2)/(6)=(1)/(3)` of rolling one of them.