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Note that it doesn't ask for the "probability" (technical term) it asks for the "likelihood" (colloquial term). Seems to me perfectly reasonable to interpret this as "... compared to the likelihood that he will pick a blue marble, and to the likelihood that he will pick a black marble". You have to interpret it as compared to something to make the answers make sense, and while the concepts "blue" and "black" appear in the question explicitly, the concept "not red" does not.

I agree with ColinsMum. It's not the world's greatest question. But I've seen worse!