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dinino66328 · 发表于 2003-7-18 17:20:00

真是不好意思，又有两题考古题百思不得其解，希望个位能伸出援手,tks.
If x, y, and d are integers and d is odd, are both x and y divisible by d?
(1) x + y is divisible by d.
(2) x – y is divisible by d.

The answer is C, Why?

If m>0 and x is m percent of y, then, in terms of m, y is what percent of x?
(1) 100m
(2) 1/100m
(3) 1/m
(4) 10/m
(5) 10,000/m
The answer is E, Why?

tocean0222 · 发表于 2003-7-18 21:59:00

1、因为x-y,x+y都能divided by d
(x+y)+(x-y)=2x，（x+y）-（x-y）=2y 也能被d divided
d 是odd，所以x,y都能被d divided

2、由题意 x=y*m%
y=x/m%=x*(m/10000)%
所以E,别忘了乘100%

dinino66328 · 发表于 2003-7-18 23:33:00

以下是引用tocean0222在2003-7-18 21:59:00的发言：
1、因为x-y,x+y都能divided by d
(x+y)+(x-y)=2x，（x+y）-（x-y）=2y 也能被d divided
d 是odd，所以x,y都能被d divided

2、由题意 x=y*m%
y=x/m%=x*(m/10000)%
所以E,别忘了乘100%

太感謝了，版主功力高深，三兩下就解決我的難題了，真的非常感謝您!

tocean0222 · 发表于 2003-7-18 23:40:00

dinino66328 ,
夸奖了，不用客气！

mike1999 · 发表于 2003-7-19 11:29:00

同意TOCEAN!

兩題考古題請看看吧