The complement probability is the probability to have the reverse side in all 3 tosses, which is equal to = .
Therefore, the probability under the question is = .
Answer by Shin123(626) (Show Source): You can put this solution on YOUR website! There are possible incomes. And there are 3 incomes that have exactly 1 head (1st coin has head,2nd has head,or 3rd makes head). Therefore, the probability is . The other tutor @ikleyn thought of the probability of at least 1 head, but the problem clearly questions about the probability of