Question

一家商店通常以每扇 $\$100$ 的价格出售窗户。本周每买四扇就赠送一扇。Dave 需要七扇窗户，Doug 需要八扇窗户。如果他们合在一起购买而不是分别购买，可以节省多少美元？

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：基本计数

难度评级：1200

解答：

分别购买时，Dave 买 $7$ 扇需付 $6$ 扇的钱，即 $\$600$ ；Doug 买 $8$ 扇需付 $7$ 扇的钱，即 $\$700$ ，合计 $\$1300$ 。

合起来买时共需 $15$ 扇，付 $12$ 扇的钱可得 $3$ 扇免费，费用为 $\$1200$ 。

因此节省 $\$1300 - \$1200 = \$100$ 。

所以正确答案是 A。

Buying separately, Dave gets $7$ windows by paying for $6$ ( $\$600$ ), and Doug gets $8$ by paying for $7$ ( $\$700$ ), for a total of $\$1300.$

Buying together, they need $15$ windows: paying for $12$ yields $3$ free, for a cost of $\$1200.$

The savings are $\$1300 - \$1200 = \$100.$

Thus, the correct answer is A.

2005 AMC 12A 第 4 题

答案：A

难度评级：1200

解答：

其他年份的第 4 题