标题: PREP的一道数学题目，已解决 [打印本页] 作者: 暗绯莎 时间: 2010-4-9 22:54 标题: PREP的一道数学题目，已解决 Henry purchased 3 items during a sale. He received a 20 percent discount off the regular price of the most expensive item and a 10 percent discout off the regular price of each of the other 2 items. Was the total amount of the 3 discounts greater than 15 percent of the sum of the regular prices of the 3 items? (1) The regular price of the most expensive item was $50, and the regular price of the next most expensive item was $20. (2) The regular price of the least expensive item was $15.
答案是A。。。作者: menganiu 时间: 2010-4-10 05:31
试试看，笨方法一步步来。设最贵价格为 X, 第二贵为 Y，最后一个 Z 问：20%X+10%Y+10%Z > 15% X + 15%Y + 15%Z 吗？ 由 （1） 知：X=2.5 Y >2.5Z 则 15%X + 2.5%X + 2.5%X + 10% Y +10%Z > 15%X + 5%Y + 5%Z + 10% Y +10% Z . ie >15% X + 15%Y + 15%Z