posted by fweng on .
A fair 6-sided die is rolled twice. The probability that the second roll is strictly less than the first roll can be written as a/b, where a and b are positive, coprime integers. What is the value of a+b?
Assume die is fair.
Rolling twice gives 36 outcomes, of which the second roll is strictly less than the first (successes) can be enumerated as follows:
Count how many successes there are, and divide by the size of the sample space (36).
It would be even better if you would not use various aliases.