Alright, thinking about it, its likely 3/2.
There's two dimes, you throw them once each. That's two chances to get heads.
The likelihood one of those two throws is heads is 100%, thus we have 1/2 so far. (one head, from one throw)
Now the other throw has two options, one if them heads(1/2) and when we do shit to that, it becomes ... Fuck, this worked in my head earlier.
Edit: ah yes, one guaranteed heads, two more possibilities to get heads. 3 possibilities from two throws.