Question

一家商店通常以每扇 $\$100$ 的价格出售窗户。本周商店推出买四送一活动。Dave 需要七扇窗户，Doug 需要八扇窗户。如果他们一起购买而不是分别购买，会节省多少美元？

A store normally sells windows at $\$100$ each. This week the store is offering one free window for each purchase of four. Dave needs seven windows and Doug needs eight windows. How many dollars will they save if they purchase the windows together rather than separately?

$100$

$200$

$300$

$400$

$500$

答案：A

知识点：钱币基本计数

难度评级：1170

解答：

Dave 单独购买时，付 $6$ 扇的钱并得到一扇免费窗户，达到 $7$ 扇，共 $\$600$ ；Doug 单独购买时，付 $7$ 扇的钱并得到一扇免费窗户，达到 $8$ 扇，共 $\$700$ 。分别购买总共 $\$1300$ 。一起购买需要 $15$ 扇窗户，买 $12$ 扇可获得 $3$ 扇免费窗户，共 $\$1200$ 。节省 $1300 - 1200 = 100$ 美元。

所以正确答案是 A。

Alone, Dave pays for $6$ windows and receives one free to reach $7,$ costing $\$600;$ Doug pays for $7$ and receives one free to reach $8,$ costing $\$700.$ Separately they pay $\$1300.$ Together they need $15$ windows: buying $12$ yields $3$ free, for $\$1200.$ The savings are $1300 - 1200 = 100$ dollars.

Thus, the correct answer is A.

2005 AMC 10A 第 5 题

答案：A

难度评级：1170

解答：

其他年份的第 5 题