# Calculating odds

1. Aug 27, 2007

### subhailc

the chance of a coin toss coming up heads is 1 in 2. i assume that the chance of it coming up heads twice in a row is 1 in 4; three times consecutively 1 in 8; 4 times 1 in 16; 5 times 1 in 32, etc... is this accurate? if not, how would that be calculated?

tyia

Last edited: Aug 27, 2007
2. Aug 27, 2007

### neutrino

That's right. For the first few cases you can write down the outcomes. Such as H T, HH HT TH TT, and so on, count the number of events favourable to the outcome of all tosses showing a head(which is 1 in all cases), and count the total number of outcomes. You will notice that for n tosses, the probability is $\frac{1}{2^n}$.

3. Aug 27, 2007

thanks