A jar contains 20 marbles:4 red,6 white and 10 blue.If you remove one at a time,randomly,what is the minimum number that must be removed to be certain tat you have at least 2 marbles of each colors?A) 6 B) 10 C) 12 D) 16 E) 18想问下答案是怎么
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![A jar contains 20 marbles:4 red,6 white and 10 blue.If you remove one at a time,randomly,what is the minimum number that must be removed to be certain tat you have at least 2 marbles of each colors?A) 6 B) 10 C) 12 D) 16 E) 18想问下答案是怎么](/uploads/image/z/11524713-33-3.jpg?t=A+jar+contains+20+marbles%3A4+red%2C6+white+and+10+blue.If+you+remove+one+at+a+time%2Crandomly%2Cwhat+is+the+minimum+number+that+must+be+removed+to+be+certain+tat+you+have+at+least+2+marbles+of+each+colors%3FA%29+6+B%29+10+C%29+12+D%29+16+E%29+18%E6%83%B3%E9%97%AE%E4%B8%8B%E7%AD%94%E6%A1%88%E6%98%AF%E6%80%8E%E4%B9%88)
A jar contains 20 marbles:4 red,6 white and 10 blue.If you remove one at a time,randomly,what is the minimum number that must be removed to be certain tat you have at least 2 marbles of each colors?A) 6 B) 10 C) 12 D) 16 E) 18想问下答案是怎么
A jar contains 20 marbles:4 red,6 white and 10 blue.If you remove one at a time,randomly,what is the minimum number that must be removed to be certain tat you have at least 2 marbles of each colors?
A) 6 B) 10 C) 12 D) 16 E) 18
想问下答案是怎么算出来的,如果加减呢?我尝试用概率可是不知道怎么理解,
A jar contains 20 marbles:4 red,6 white and 10 blue.If you remove one at a time,randomly,what is the minimum number that must be removed to be certain tat you have at least 2 marbles of each colors?A) 6 B) 10 C) 12 D) 16 E) 18想问下答案是怎么
中文意思是 4 红,6白,10蓝,每次随机拿一个球,问最少需要拿多少个才能确定里边含有2红、2白、2蓝.
我的思路是这样,考虑极端恶劣情况:
前10个,均为蓝.已拿10个,完成2个蓝.
再拿2个,均为白.已拿12个,完成2蓝,2白.
再拿2个,还是白.已拿14个,完成2蓝,2白.
再拿2个,还是白.已拿16个,完成2蓝,2白.
再拿2个,嗯 ,终于是红了.已拿18个,完成2蓝、2白、2红.
所以答案是E
10+6+2=18,不知道对不对啊
选18,最遭的情况是10个蓝的6个白的和2个红的都被你给拿出来了,最后才拿到第二个红的
高手啊,gre考试还有数学,英语要好到爆了才能考啊听说