# probability of at least two.

• November 2nd 2013, 03:18 AM
anthonye
probability of at least two.
Hi;
I'm having trouble with this question.

Three coins are tossed what is the probability of getting three
heads if it is known that at least two heads were obtained?

Thanks.
• November 2nd 2013, 03:33 AM
Plato
Re: probability of at least two.
Quote:

Originally Posted by anthonye
three coins are tossed what is the probability of getting three
heads if it is known that at least two heads were obtained?

$\\thh\\hth\\hht\\hhh$
• November 2nd 2013, 03:36 AM
anthonye
Re: probability of at least two.
So the answer is 1/2. I just want confirmation because my book says 1/4.
• November 2nd 2013, 03:39 AM
anthonye
Re: probability of at least two.
OH also the formula is it P(A given B) = (A and B)/P(B) I sure this is correct but whats P(A and B) in this question.

Thanks.
• November 2nd 2013, 05:56 AM
HallsofIvy
Re: probability of at least two.
Quote:

Originally Posted by anthonye