Flipping a coin has a 50:50 chance. The only way to get close to the expected ratio is to flip a lot of times. It is never guaranteed.
If you're trying to get a certain 50/50 chance for flipping a coin make sure it is different on both sides and isn't dodgy.
The probability of flipping a coin 3 times and getting 3 heads is 1/2
You can't be sure to get the 50/50 ratio of heads and tails. Each time will be a trial & error.
There are 8 permutations of flipping a coin 3 times, or of flipping 3 coins one time. They are, with the permutations of two heads bolded...TTTTTHTHTTHHHTTHTHHHTHHH... thus, the probability of flipping a coin 3 times and getting 2 heads is 3 in 8, or 0.375.
The event is that the coin lands with the Heads on top.
.5 or 1/2
1/4
As a coin has two sides, the odds are always 50-50.
You can never be sure. The more often you toss it the closer the probability gets to a 50-50 split but there is no guarantee.
1 in 2.
1/4
.125