2
$\begingroup$

I have a question I have worked out and I would like to check my solution. I am told that 4 fair coins are tossed in succession. I am to find the probability of getting 4 tails given that the first 2 tosses were all tails.

I got $\frac{1/16}{1/4} = \frac{1}{4}.$ Is this right?

  • 0
    @count: You can answer your own question now that you know the right answer.2012-06-07

1 Answers 1

1

As Brian said in the comment, what we want is the probability that last two tosses are both tails. Since the probability of getting a tail is $\frac{1}{2}$, we get $ \frac{1}{2}\cdot \frac{1}{2}=\frac{1}{4}.$