Re: [計量] At a sale, the cost of each tie ...
※ 引述《lonnan (far away)》之銘言：
: 有兩題計量想請教各位怎麼算
: 先謝謝了
: 1. At a sale, the cost of each tie was reduced by 20 percent and the cost of e
: ach belt was reduced by 30 percent.
: Column A
: The percent reduction on the total cost of 1 tie and 2 belts
: Column B
: 25%
: ans: 我是選 B (A < B)，但答案卻是 D (無法判斷)
設the cost of each tie was x dollars
the cost of each belt was y dollars
Column A = (0.2x+0.3y*2)/(x+2y)=0.2+ (0.2y/x+2y)
最後代數那項無法確定 所以選D
: 2. For the line with equation y=ax+b, ab < or > 0, the x-intercept is twice the
: y-intercept.
: Colunmn A
: The slope of the line
: Column B
: 1/2
x-intercept = -(b/a)
y-intercept = b
-(b/a)= 2*b a=-1/2 = the slope of the line
所以應該是選B
應該是這樣吧
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