求助几道GWD上的数学题

RoadtoAmerica · 发表于 2012-7-2 13:41:36

1，图形打不出来，我简单描述一下，一个半弧形的截面，底长为20feet

The figure above shows the dimensions of a semicircular cross section of a one-way tunnel. The single traffic lane is 12 feet wide and is equidistant from the sides of the tunnel. If vehicles must clear the top of the tunnel by at least ½ foot when they are inside the traffic lane, what should be the limit on the height of vehicles that are allowed to use the tunnel? B

A.   5½ ft
B.   7½ ft
C.   8 ½ ft
D.   9½ ft
E.   10 ft

2，On a certain transatlantic crossing, 20 percent of a ship’s passengers held round-trip tickets and also took their cars abroad the ship. If 60 percent of the passengers with round-trip tickets did not take their cars abroad the ship, what percent of the ship’s passengers held round-trip tickets? C

A.   33 1/3%
B.   40%
C.   50%
D.   60%
E.   66 2/3%

3，In a corporation, 50 percent of the male employees and 40 percent of the female employees are at least 35 years old. If 42 percent of all the employees are at least 35 years old, what fraction of the employees in the corporation are females? D

A.   3/5
B.   2/3
C.   3/4
D.   4/5
E.   5/6

像第二第三道这种percent的题，prep和GWD上有很多，有没有什么技巧或者套路啊？求指点~谢啦~

shawntsao · 发表于 2012-7-2 14:00:17

第二题：
1. 总人数的20% 是有往返票又带着车的
2. 60%的有往返票的人是没带车的 --------得出：40%有往返票的人是带着车的

1=2 ------- 20%总人数=40%有往返票的-----------有往返票的/总人数= 1/2

shawntsao · 发表于 2012-7-2 14:04:28

第三题：
设：男员工人数为m, 女员工人数为n
50%m+40%n=42%（m+n)------------得出：4m=n

所以 n/m+n = 4:5

shawntsao · 发表于 2012-7-2 14:24:22

第一道：
由图可知：半径是10
由题可知：路宽的一半是6

作个直角三角形，可得另一个直角边（也就是高）是8
8-1/2= 7 1/2

没有图LZ见谅，我开始也不会，要理解一下题意，别被吓到……

Roxanne19 · 发表于 2012-7-2 17:18:04

和我的问题一样感谢各位大侠的回答很有帮助

求助几道GWD上的数学题

所属分类: GMAT考试

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