Question 1056943
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. &#9786;&#9786;&#9786;&#9786;
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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. &#9786;&#9786;&#9786;&#9786;