Question

Need help

Answer 1

Probability to get 5 when rolled once = 5/(1+2+3+4+5+6) = 5/21

Probability to not get 5 when rolled once = 1 - 5/21 = 16/21

Probability to not get 5 when rolled twice = (16/21)^2 = 256/441

Probability to get 5 at least once when rolled twice = 1 - 256/441 = 185/441

Answer 2

Weighted implies the die is rigged.  All normal bets are out the window at that point, you'd have to ask the person who weighted the die where the weight is for starters.  Then it's a matter of, are the five sides that aren't weighted still equal probability relative to each other or is it completely and randomly skewed?

The way it's stated, this isn't a simple question.

Answer 3

No way to know without infirmation on how is it weighted.