maths probability question

1/8 sounds good.

Hiya, came across this question:
If you throw 4 coins, what is the probability the first two are heads and there are exactly three heads?

I got 2/16 but I don't know if it is right. If someone cold have a little look for me I'd be very grateful.

That is 1/8. I think you are right. Your probability you have to determine is at least to get three heads in a row, four at the maximum.

So your probabilities they come into questions are:

H-H-H-N and H-H-H-H (N stands for number)

Those are two probabilities out of 16 possible, so 2/16 or just 1/8. Well done!

Here Kallisto means H-H-H-N and H-H-N-H - the two ways of making 3 heads with 2 at the beginning