GWD31-15一道数学求助~~~

dolorez

On a certin transatlantic crossing,20 percent of a ship's passengers held round-trip tickets and also took their cars broad the ship.If 60 percent of the passengerswith round-trip tickets did not take their cars abroad the ship,what percent of the ship's passengers held round-trip tickets?
A.20% B 30%  c.50% D60% E 60%

nicolewitch

我觉得这个题有问题啊,你不可以assume那两个took cards的量是相等的哎,因为20 percent of a ship's passengers held round-trip tickets and also took their cars broad the ship,那如果没有round-trip T的人里也有take cads的呢,是我理解的太复杂了还是题干本身就有点问题啊,不知道LZ怎么个理解法。。。我老是把问题复杂化,哎

genius_fang

选C吧~说乘客总人数中20%有r-t并且 took their cars broad ，然后又r-t的人里面60%没有  took their cars broad ，言下之意，有r-t的人里面40% took their cars broad 。所以设总人数x，有r-t的y，40%y=20%x算出来y占50%