Re: Number of Essay questions that I have to do.
As an alternate solution:
With 3 picks the probability of the first choice not being studied is 3/6. If the first choice is not studied the probability of the second test not being studied is 2/5. The probability of neither pick being studied is then (3/6)(2/5)=6/30=20%. Hence the probability of either pick being studied with three tests studied is 1-20%=80%.
Paul
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