I'm working on a maths exercise and came across this question.
The probability of a "heads" when throwing a coin twice is 2 / 3. This could be explained by the following:
• The first time is "heads". The second throw is unnecessary. The result is H;
• The first time is "tails" and twice "heads". The result is TH;
• The first time is "tails" and twice "tails". The result is TT;
The outcome: {H, TH, TT}. two of the three results include a "heads", it follows that the probability of a "heads" is 2/3
What's wrong with this reasoning?
I think the answer is 1/2, is that right?
Ps. my first language isn't english,
Thanks Jef