260. Of vehicles( car+truck), 48% are 4 door cars. 80% of the cars are 4 door. What’s the proportion of cars that is not 4 door to the population of vehicle?
The answer is 12%
265 of the veichles (cars and truck) on sale, 48% of the cars are 4-door. 80% of the sale cars are 4-door. 问，有多少%的veichle是不是4-door的，完全没懂。我选了个20%。。。。答案有12%什么的。忘记了。
汇总一下：总车的48%是四门，轿车的80%是四门（设为X），问非四门占总车多少Percent
(1-80%)/80%*X除以X/48%=12%
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这道题看不懂答案原理。vehicles=casr+trucks 答案所列的好像没有考虑到trucks 有NN知道这个答案的原理吗？如果答案是对的。。。-- by 会员 wfuwa (2010/1/24 14:17:03)
48%fourdoor cars, 12% non-fourdoor cars(48%/.8=12%/(1-.8)), 40% trucks (1-.48-.12) -- by 会员 jacob (2010/1/24 14:38:28)
谢谢回答。不过没看诶。如果48%是所有四车门car占total vehicles的比例，20%/(0.8/48%)=12% . 如果48%并不仅仅是四车门的car还有四车门的truck，就不应该是12%了吧 | 
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发表于 2010-1-24 14:17:03
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