We have coin lying on table.
we have to select one coin ad then toss it.
In starting we have {H,H,T } outcome
Now from here we can only select one coin then flip it.
So,number of all posible outcomes are those which have 1 or 0 hamming distance from above outcome.
Here total outcomes are ---6
And outcomes with at least two heads are----4
Ans is=4/6=2/3