# What is the probability that the first toss was the tail?

1. Jan 10, 2009

### tictac123

1. The problem statement, all variables and given/known data
A coin is tossed 3 times and you note that the coin lands heads exactly twice. What is the probability that the first toss was the tail?

3. The attempt at a solution

I've solved the problem manually not using notation.

So I want to try to solve with notation?

Thanks

2. Jan 10, 2009

### rock.freak667

Re: Probability

I am not familiar with the notation you speak of, can you give me an example of what you're asking for?

3. Jan 10, 2009

### sutupidmath

Re: Probability

p(the coin landed tail)=.5

4. Jan 10, 2009

### tictac123

Re: Probability

Without using nCr
But Conditional Prbability

5. Jan 10, 2009

### NoMoreExams

Re: Probability

Well what answer did you get? :)

6. Jan 10, 2009

### icystrike

Re: Probability

i also learning probability and just to ask those who have completed this, is the answer 1/6 ?

7. Jan 10, 2009

### Delphi51

Re: Probability

Tricky! I'm thinking of a manual solution like this:
The possible outcomes are HHT, HTH, THH.
BUT I'm wondering if I need to distinguish between the two H's so it is
HhT, hHT,HTh,hTH,THh,ThH