Question

一家商店广告称“今天促销所有商品半价”。此外，一张优惠券可在促销价基础上再打八折。使用优惠券后，今天的价格相当于原价的百分之多少折扣？

A shop advertises that everything is "half price in today's sale." In addition, a coupon gives a 20% discount on sale prices. Using the coupon, the price today represents what percentage discount off the original price?

$10$

$33$

$40$

$60$

$70$

答案：D

知识点：百分数

难度评级：980

视频讲解：

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文字解答：

设原价为 $p$ 。半价后价格为 $0.5p$ 。

再打 $20\%$ 折扣表示支付价格的 $80\%$ ，所以最终价格为 $0.5p\cdot 0.8 =0.4p$ 。

因此减少了 $0.6p$ ，折扣率为 $\dfrac{0.6p}{p} = 0.6$ ，即 $60\%$ 。

所以正确答案是 D。

Let $p$ be the original price. If everything is half off, we have the new price as $0.5p.$

Having a $20\%$ discount makes it such that we keep $80\%$ of the price, so the price is $0.5p\cdot 0.8 =0.4p.$

This would have $0.6p$ off, so we get a discount of $\dfrac{0.6p}{p} = 0.6,$ which is $60\%.$

Thus, the answer is D .

2012 AMC 8 第 8 题

答案：D

难度评级：980

视频讲解：

文字解答：

其他年份的第 8 题