prep ds1 205不对吧?

sophialj

Ellen can purchase a certain computer at a local store at the price of p dollars and pay a 6 percent sales tax.  Alternatively, Ellen can purchase the same computer from a catalog for a total of q dollars, including all taxes and shipping costs.  Will it cost more for Ellen to purchase the computer from the local store than from the catalog?

 

(1) q - p < 50

 

(2)
                q = 1,150

--------------------------------------------------------------------------------------------------------------------------------------------------------【答案】C

【思路】

(1) 不知道p的6%是否大於50

(2) 沒有相對於p的條件

(1)+(2) (1150-50)x(6/100)=66 (銷售稅大於差價)     我也算到这了阿??

[另解]

C1 = p + 0.06p, C2 = q
(1) q - p < 50 not sufficient
(2) p = 1,150 --> C1 = 1,219 not sufficient
(1) + (2) C2 - C1 = q - ( p + 0.06p) = q - p - 0.06 x 1,219 = (<50) - 73.14 < 0
so it costs more for Ellen to purchase the computer from the local store than from the catalog

明明题目给的q=1150,怎么解释变成p=1150。如果按原题做答案应该是E吧？

Ans C

Ans C

sophialj

不好意思耽误大家时间，我已经知道怎么做了，

哈利波米

q=1150 q-p<50  so p>1100  so 1.06p>q 条件就充分了

哈利波米

以下是引用sophialj在2009-6-10 20:51:00的发言：
不好意思耽误大家时间，我已经知道怎么做了，

呃。。。