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题库 / Prep2007E1-DS-2
Of the students who eat in a certain cafeteria, each student either likes or dislikes lima beans and each student either likes or dislikes brussels sprouts. Of these students, ~$\frac{2}{3}$~dislike lima beans; and of those who dislike lima beans, ~$\frac{3}{5}$~also dislike brussels sprouts. How many of the students like brussels sprouts but dislike lima beans?
(1) 120 students eat in the cafeteria.
(2) 40 of the students like lima beans.
Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
EACH statement ALONE is sufficient.
Statements (1) and (2) TOGETHER are NOT sufficient.
转载：
题目是问你P(A+B) = P(A) + P(B) - P(AB)
1. P(AB)=0是不充分的.因为如果同时发生的概率为0那么说明白球上都不是偶数,但是不代表不是偶数的都是白球.所以不充分
所以锁定选项B/C/E
2. 白球的概率-偶数概率为0.2,P(A) - P(B) = 0.2 .无法解出 P(A) + P(B)
所以两个加起来也不充分
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