That's the most interesting and informative issue presented by this scenario.
The problem with the sort of test you propose is that just because a human uses intelligence to solve a problem, it does not follow that the task requires intelligence. For example, playing chess.
From an engineering point of view, your black box may be as good as the real thing, though you couldn't really trust it beyond the areas of its demonstrated competence. Knowing how it works, however, would be the most significant achievement.
Furthermore, it's going to be hard to build one of these black boxes without a reasonably good idea of how it is going to work.
There is also the risk that your weighting scheme will rule out the only algorithms that have a chance of succeeding, because I bet they are pretty complex.
That's the most interesting and informative issue presented by this scenario.
The problem with the sort of test you propose is that just because a human uses intelligence to solve a problem, it does not follow that the task requires intelligence. For example, playing chess.
From an engineering point of view, your black box may be as good as the real thing, though you couldn't really trust it beyond the areas of its demonstrated competence. Knowing how it works, however, would be the most significant achievement.
Furthermore, it's going to be hard to build one of these black boxes without a reasonably good idea of how it is going to work.
There is also the risk that your weighting scheme will rule out the only algorithms that have a chance of succeeding, because I bet they are pretty complex.