Answer: choice B) 3/7
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Explanation:
There are 8+3+4+22 = 37 items total.
Using the conditional probability formula, we can say
P(Q|R) = [P(Q and R)]/P(R)
P(Q|R) = (3/37)/(7/37)
P(Q|R) = (3/37)*(37/7)
P(Q|R) = 3/7
Put another way, we know that event R has happened. We know that the value is drawn out of circle R. So we have 7 possible outcomes. Of those 7, three of them are in both Q and R. So that's another viewpoint of why the answer is 3/7.
