Problem 22 of 25sta-022
A fair number cube with faces numbered 1 through 6 is rolled twice. What is the probability that at least one of the two rolls shows a 6?
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Solution walkthrough1:44
- "At least one " covers several cases. Its opposite, "no at all", is one simple case.
- Two rolls give outcomes, all equally likely.
- No : both rolls are to , so outcomes, a chance of .
- At least one is everything else: .
- Traps: adds , counting double six twice. forgets to subtract from .