Question 1180142
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There are 2 possible outcomes for each coin -- heads or tails.<br>
For four coins, the total number of possible outcomes is 2^4=16.<br>
There are 4 ways you can get exactly one head: it can be any one of the four coins.<br><pre>
                       # of ways of getting one head     4     1
P(exactly one head) = ------------------------------- = --- = ---
                       total # of possible outcomes     16     4</pre>