in township K,1/5 of the housing units are equipped with cable television. if 1/10 of the housing units, including 1/3 of those that are equipped with cable television, are equipped with videocassette recorders, what fraction of the housing units have neither cable television nor videocassette recorders?
A) 23/30
B) 11/15
C) 7/10
D) 1/6
E) 2/15
答案是A，给的解答是 1 - 1/5 - 1/10 + 1/15= 23/30
我觉得不对啊，应该是 1 - 1/5 - （1/10 * 2/3）= 11/15
应该选B才对啊
我错在哪了？作者: zeus99 时间: 2002-12-9 15:39
a=1/5,b=1/10,
a and b =(1/5)*(1/3)=1/15
so N=1-a-b-(a and b)=.....作者: biandy 时间: 2002-12-9 20:25
哎呀哎呀，大误会！
我当时怎么会想歪了呢？应该是1/5的1/3，我却认为是1/10的1/3，看来读题还是有问题：（
谢谢：）
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