Flip a fair coin 25 times. what is the size of the sample space? that is, how many different sequences of heads and tails are possible? what is the probability of each one of those possible outcomes?
There are 50% chance's that it would land on heads or tails. there could be many different outcomes like (H) for heads and (T) for tails many times like this H, T, H, T, H, T.
