2. 职称英语
  3. Bowls X and Y each contained exactly 2 jelly beans， each of which was either red

Bowls X and Y each contained exactly 2 jelly beans， each of which was either red

游客2024-01-13  66
问题 Bowls X and Y each contained exactly 2 jelly beans， each of which was either red or black．One of the jelly beans in bowl X was exchanged with one of the jelly beans in bowl Y， After the exchange．were both of the jelly beans in bowl X black?
(1) Before the exchange，bowl X contained 2 black jelly beans．
(2) After the exchange，bowl y contained 1 jelly bean of each color．
选项 A、Statement(1) ALONE is sufficient，but statement (2) alone is not sufficient．
B、Statement(2) ALONE is sufficient．but statement (1) alone is not sufficient．
C、BOTH statements TOGETHER are sufficient．but NEITHER statement ALONE is sufficient．
D、EACH statement ALONE is sufficient．
E、Statements(1) and(2) TOGETHER are NOT sufficient．
答案 E
解析 Determine after an exchange of one jelly bean if both jelly beans in bowl X are black.
(1)     Bowl X has two black jelly beans, but bowl Y could have two red or two black or one of each color. If bowl Y has two red jelly beans, then bowl X will have one red and one black jelly bean after the exchange, not two black. However, if bowl Y has two black jelly beans, then bowl X will have two black after the exchange; NOT sufficient.
(2)     After the exchange, bowl Y has one red and one black. If, before the exchange, bowl X had two black and bowl Y had two red, then after the exchange, each of bowl Y and bowl X will have one of each color. However, if bowl Y had two black jelly beans, bowl X had one of each color, and bowl X obtained a black in exchange for the red, then bowl Y will have one of each color and bowl X will have two black; NOT sufficient.
Taking (1) and (2) together, bowl X had two black jelly beans to start with and bowl Y ended up with one of each color after the exchange, bowl Y had to have had at least one red because bowl X had no red jelly beans to give to bowl Y. If bowl Y has two red and exchanges a red for one of bowl Xs blacks, then, after the exchange, bowl Y will have one of each color, but bowl X will not have two black. On the other hand, if bowl Y has one of each color and exchanges its black for one of bowl Xs blacks, then after the exchange, bowl Y will have one of each color and bowl X will have two blacks.
The correct answer is E;
both statements together are still not sufficient.
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