Question

A coin is tossed seven times. Find the probability of getting exactly four heads.

Answer 1

exactly four heads means the events of 4H's (head) and 3T's (tail)
the numbers events of 4H and 3T is = 7!/(4!3!) = ....
and we knowed that the probability for 1H = 1/2 and also the probability for 1T = 1/2. assuming this event is independence for each tossed, so
the total of probability of getting exactly four heads can be :
P(4H, 3T) = 7!/(4!3!)*(1/2)*(1/2)*(1/2)*(1/2)*(1/2)*(1/2)*(1/2) = ... ?