求解数学题

呆呆佳 · 发表于 2012-3-19 16:45:03

If 55 percent of a group of people have broen hair and 80 percent of the same group do not have red hair, what fraction of those who do not have brown hair have red hair?
A 1/4
B 4/11
C 4/9
D 5/9
E 4/5
答案为C
不知道怎么解的求解啊

mxxdm88 · 发表于 2012-3-24 15:36:12

设有group里有X个人，那红发人占非棕发人的比例为 (1-80%)x/(1-55%)x = 4/9

呆呆佳 · 发表于 2012-3-25 12:54:35

谢谢谢谢

求解数学题

所属分类: GRE考试

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