- #1
stosw
- 21
- 0
Homework Statement
Roll a fair die until the first time you roll a '5' then stop. Let X be the number of times you rolled the die. What is the probability that X is divisible by 3?
Homework Equations
E[X] ?
The Attempt at a Solution
I honestly have no idea how to even approach this sort of thing. My first thought was either a bionomial or geometric series, but that could possibly be endless.
any sort of hints or suggestions would be great.