15 marbles are placed in a bowl; some are red, and some are blue. If the number of red marbles is 1 more than the number of blue marbles, what is the probability that a marble taken from the bowl is blue?
A.115
B.215
C.715
D.12
E.815
我的答案:
15 marbles are placed in a bowl; some are red, and some are blue. If the number of red marbles is 1 more than the number of blue marbles, what is the probability that a marble taken from the bowl is blue?