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标题: GMAT Prep #20 [打印本页]

作者: uspresident 时间: 2006-6-16 06:49 标题: GMAT Prep #20

20. DS, in a work force, the empolyees are either managers or directors. What is the percentage of directors?

a) the average salary for managers is $5,000 less than the total average salary

b) the average salary for directors is $15,000 more than the total average salary

answer is C)

Let x = percentage of directors and 1-x = percentage of managers,

A = average salary for managers and B = average salary for directors

I listed two equations based on the two conditions:

B+5000 = [A*x + B*(1-x)] / (x + 1-x)

A-15000 = [A*x + B*(1-x)] / (x+1-x)

2 equations, 3 unknowns. Shouldn't the answer be E?

作者: lingri88 时间: 2006-6-18 08:25

QUOTE:

B+5000 = [A*x + B*(1-x)] / (x + 1-x) (1)
A-15000 = [A*x + B*(1-x)] / (x+1-x) (2)

可得A=B+20000

代入(1)

B+5000=BX+20000X+B-BX

X=1/4

所以有的DS题是比较烦,粗看无解,如果实际算一下是可以解出来的.

我觉得在总的答题时间足够的情况下还是解一下,以免碰到这种情况.

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