A coin is tossed $n$ times. What is the probability of getting odd number of heads? 
A coin is tossed $n$ times. What is the probability of getting odd number of heads?

I started this chapter sometimes ago and faced in front of a tough problem. At first I started considering cases. Case-I : The probability of getting 1 head.Case-II : The probability of getting 3 head and so on. But there are many cases. So how can I solved this . Please help me. Thank you!

First toss $n-1$ times. When you toss the $n^{th}$ time, one outcome will give an even number of heads and one outcome an odd number of heads.
If the coin is a fair coin, this gives the result immediately. If it is not, then you need to combine the probabilities of odd/even after $n-1$ tosses with the probabilities on the last toss as Robert Z has done, or sum the binomial.
