There is a unfair coin and you want to find out its actual probability, to find the exact probability is actually not an easy task, you need to toss it many many times to get the close to actual result.
Gladly, someone has already calculated that and he is observing you while you are tossing. You toss the coin 4 times at the beginning, and get 2 tails and 2 heads as THTH. Then all of a sudden the observer said:
The chance of getting $2$ tails and $2$ heads with this coin is actually half of the probability of getting a tail in a single toss with it.
By this information,
Can you find the most probable probability of getting a tail in a single toss with this coin?