2012 AMC 8 第 8 题
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所有题目均经美国数学协会（MAA）官方合法授权使用。
8.
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享受 的折扣。使用优惠券后，今天的价格相对于原价的折扣率是多少？
A shop advertises that everything is “half price in today’s sale.” In addition, a coupon gives a discount on sale prices. Using the coupon, the price today represents what percentage discount off the original price?
答案：D
小提示：
半价后，促销价是原价的 。
After half price, the sale price is of the original.
大提示：
优惠券让价格保留促销价的 。
The coupon keeps of the sale price.
视频讲解：
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文字解答：
设原价为 。半价后价格为 。
再打 折扣表示支付价格的 ，所以最终价格为 。
因此减少了 ，折扣率为 ，即 。
所以正确答案是 D。
Let be the original price. If everything is half off, we have the new price as
Having a discount makes it such that we keep of the price, so the price is
This would have off, so we get a discount of which is
Thus, the answer is D .
其他年份的第 8 题
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