What you have calculated is the probability that, if you flip two coins, a penny and a coin made in 2008, one or both of them will come up heads. This is analogous to the sprinkler/rain problem—the grass can be wet by either or both of two independent events.
I’m not sure if there is a way to find P(heads | 2008 and penny) using only the information given, but I don’t think a computer program would be confused by this kind of thing if it kept rigorous track of the events that its probabilities refer to.
What you have calculated is the probability that, if you flip two coins, a penny and a coin made in 2008, one or both of them will come up heads. This is analogous to the sprinkler/rain problem—the grass can be wet by either or both of two independent events.
I’m not sure if there is a way to find P(heads | 2008 and penny) using only the information given, but I don’t think a computer program would be confused by this kind of thing if it kept rigorous track of the events that its probabilities refer to.