1950 AMC 12 第 36 题

先试着解答 1950 AMC 12 第 36 题,然后核对你的答案与精心整理的解答,解答来自 LIVE by Po-Shen Loh。你也可以参加完整限时模拟考试、查看全部 1950 AMC 12 解答,或核对答案。

所有题目均经美国数学协会(MAA)官方合法授权使用。

36.

一位商人以比目录价低 25%25\% 的价格购入商品。他希望设定一个标价,使商品按标价打 20%20\% 的折扣售出后,利润仍为售价的 25%25\%。标价应为目录价的百分之几?
A merchant buys goods at 25%25\% off the list price. He desires to mark the goods so that he can give a discount of 20%20\% on the marked price and still clear a profit of 25%25\% on the selling price. What per cent of the list price must he mark the goods?
125%125\%
100%100\%
120%120\%
80%80\%
75%75\%
答案:A
知识点:百分数钱币一次方程
小提示:
设目录价为 LL,标价为 MM
Take the list price to be LL and the marked price to be MM
大提示:
成本为 0.75L0.75L,售价为 0.8M0.8M,且成本是售价的 75%75\%
The cost is 0.75L,0.75L, the selling price is 0.8M,0.8M, and the cost is 75%75\% of the selling price
解答:
设目录价和标价分别为 LL 和 MM。商人的成本为 0.75L0.75L,打折后的售价为 0.8M0.8M。利润等于售价的 25%25\%,意味着成本是售价的其余 75%75\%。因此, 0.75L=0.75(0.8M)=0.6M。 0.75L=0.75(0.8M)=0.6M\text{。}所以 M=1.25LM=1.25L,即目录价的 125%125\%。
因此,正确答案是 A。
Let the list and marked prices be LL and M.M. The merchant’s cost is 0.75L,0.75L, while the selling price after the discount is 0.8M.0.8M. A profit equal to 25%25\% of the selling price means that the cost is the remaining 75%75\% of that price. Therefore 0.75L=0.75(0.8M)=0.6M. 0.75L=0.75(0.8M)=0.6M. Thus M=1.25L,M=1.25L, or 125%125\% of the list price.
Thus, the correct answer is A.
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