Question 1056943: A coin is tossed four times. Assuming that the coin is equally likely to land on heads or tails, compute the probability of the event occurring.
At least two tails
Answer by jorel555(1290)   (Show Source):
You can put this solution on YOUR website! Let's find the probability of three heads. This is 1/2 x 1/2 x 1/2. This is 1/8. So the probability of getting at least two tails is 1-1/8, or 7/8. ☺☺☺☺
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(Previous answer was WRONG! SORRY!)
After further review, we look at the problem a different way. The only possible permutaions are
HHHH, HHHT, HHTH, HTHH, THHH, HHTT, HTHT, HTTH,
TTTT, TTTH, TTHT, THTT, HTTT, TTHH, THTH, THHT
If we look at this, we see that there are 11 ways out of 16 in which we get at least 2 tails, making our probability 11/16, or .6875. ☺☺☺☺
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