Question

Rolling an 8-sided die, after 5 rolls, what is the probability of at least 1 number being rolled twice?

Answer 1

The probability of at least one number appearing twice in five rolls is `407/512`.

Explanation:

The probability of no number occurring twice after five rolls is `8/8*7/8*6/8*5/8*4/8 = 105/512`.

To get the probability of at least one number occurring twice, subtract the above probability from `1`:
`1-105/512 =407/512`