Question 1117491
There are {{{2^3=8}}} 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 {{{3/8}}}. The other tutor @ikleyn thought of the probability of at least 1 head, but the problem clearly questions  about the probability of <H2>1</H2> head.