What is probability of
at least 3 heads appearing in 4 tosses of a coin
There are a total of 2^4=16 outcomes, out of which 4 heads are in (4,4)=1 case, and 3 heads are in (4,3)=4 cases.
So the probability of tossing at least 3 heads is
P(3H)=((4,4)+(4,3))/2^4=(1+4)/16=?