Question

You toss 3 coins . What is the probability that you get exactly 2 heads, given that you got at least 1 head? A tree diagram will help you answer this question

Answer 1

There is one possibility where you get no heads.
There are three possibilities where you get 1 head.
There are three possibilities where you get 2 heads.
There is one possibility where you get 3 heads.

But we don't count the possibility where you get no heads at all. So we only have seven possibilities that we're dealing with.

So, the odds are 3/7.

Answer 2

I think its 1/2.

Answer 3

The tree diagram shows 8 equally likely possible outcomes. We must exclude the TTT outcome because it is given that you get at least 1 head.

Count all of the branch paths that show exactly 2 heads. There are 3 of them. There are 7 possible outcomes because we eliminated one of them.

Therefore, the probability of getting exactly 2 heads in this problem is 3/7.

Answer 4

where do you get the 7 from

Answer 5

total number of outcomes

Answer 6

since you have 1 head, the possibilities withe the other 2 are:
HH, HT, TH, TT.
Since you need exactly 2 heads, 2 of the above 4 possibilities are desirable.
therefore \[P=\frac{2}{4}=\frac{1}{2}\]

Answer 7

and how do you get the total number of outcomes