[原创]机经

顾风

谢谢楼主分享。。

顾风

1. DS: appartments avg. rent $600, what is the percentage of appartments with rent under $600? 1) exactly half of the appartments with rent under $500;  2) the rents of differnt appartments are either $450, $550, $650, or $800.

这道题我算了8分钟才把 1)+2) 的正反例子都找出来。

p1+p2+p3+p4 = 1

p1 = .5

p2+p3+p4=.5

p2*550+p3*650+p4*800 = 600- 225 =375

p2*22+p3*26+p4*32 = 15

此解为任意解。。。

如 p2 = .1,则p3 = 0, p4=0.4

  p2 = .008 则 p3 =x,p4=y...