Question

a coin is tossed what probability head will come up ?

Answer 1

Well, very strictly speaking, it is 0% as you cannot have both heads and tail show at the same time (1 toss). If you mean either heads or tail it would be 100% as a coin usually only has two sides and one or the other would show. But again, strictly speaking, it could land on its edge and not fall down to show one or the other side being up in which case it would only be 99.999999999999 % chance.
If you mean to ask what is the probability of heads, I would say it is somewhere between 0% and 100%, maybe closer to 50%. For one toss only there is great uncertainty even though it mathematically should be 1 out 2 making it 50%. You would have to make many tosses to get closer to a realistic 50% chance. So don’t gamble on it. And we have of course only considered a perfect coin and a perfectly random toss in a perfect world. :)

Answer 2

Total no. of outcomes = Head, tail = 2
No. of possible outcome = Head = 1
Probability that we get a head when the coin is tossed
 = No. of possible outcomes/Total no. of outcomes
= 1/2
= 0.5

So, the probability that we get a head when the coin is tossed is 0.5

Hope this helps you.