# Math Help - coin probability

1. ## coin probability

You have 5 coins and one is double sided Head. If you pick one coin up at random and flip it 5 times and get 5 Heads in a row, what is the probability that you have been flipping the double sided Head coin?

-Thanks.

2. I'm going to assume that each coin is chosen with equal probability, which is 0.2.

Then the probability you picked the double head coin is:

$\frac{0.2}{0.2(1 + 4 \cdot 0.5^5)} = \frac{8}{9}$

3. Originally Posted by curious444
You have 5 coins and one is double sided Head. If you pick one coin up at random and flip it 5 times and get 5 Heads in a row, what is the probability that you have been flipping the double sided Head coin?

-Thanks.
I think for this question you could use the binomial distribution.
n = 5 and the probability of choosing the double headed coin will be 1/5