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?
A.33 1/3%
B.40%
C.50%
D.60%
E.66 2/3% 作者: sdcar2010 时间: 2011-6-5 11:16
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?
If 60 percent of the passengers with round-trip tickets did not take their cars abroad the ship, then 40% of the passengers with round-trip tickets DID take their cars abroad the ship. So 20% is only 40% of the total for passengers held round-trip tickets.
The answer should be 50%作者: SeeSee666 时间: 2016-10-10 06:55
这样的题，画一个表格，就很清晰了。
可以列为：
cars no cars 总计
roundtrip 0.2 t 0.6a a
no roundtrip
t
（解释： 总共的passenger 为t， 所有有往返票的为a，注意审题 Of）
所以， people with roundtrip ticket+ cars =0.2t=0.4a
那么， 0.4a=0.2t,
a=0.2t/0.4=0.5 t
答案为： 50%