Question

Your friend is tossing a coin. He says that heads and tails are equally likey outcomes, so the probability of getting heads is 50/50. Explain your friends error.

Answer 1

There is no error if you are talking about just one toss.
Prob. of head = 50%
Prob. of tail = 50%

See http://www.members.cox.net/dagershaw/lol/Odds.html