
Mark M. answered 05/04/15
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Mathematics Teacher - NCLB Highly Qualified
First determine the total number of outcomes: 6 x 6 x 6 x 6 x 6 = 7776.
Now determine the number of successes.
Say the first roll is NOT a two and the rest are. That can happen 5 ways.
Say the second roll is NOT a two and the rest are. That can happen 5 ways.
Say the third roll is NOT a two and the rest are. That can happen 5 ways.
Say the fourth roll is NOT a two and the rest are. That can happen 5 ways.
Say the fifth roll is NOT a two and the rest are. That can happen 5 ways.
So far 25 successes, yet there is one more - all five rolls are 2's.
The probability of rolling at least four 2's is 26/7776