Question

Orvin 去商店时带的钱刚好够买 $30$ 个气球。到店后，他发现气球正在促销：按原价买 $1$ 个气球，第二个可减价 $\frac{1}{3}$ 。Orvin 最多可以买多少个气球？

Orvin went to the store with just enough money to buy $30$ balloons. When he arrived, he discovered that the store had a special sale on balloons: buy $1$ balloon at the regular price and get a second at $\frac{1}{3}$ off the regular price. What is the greatest number of balloons Orvin could buy?

$33$

$34$

$36$

$38$

$39$

答案：C

知识点：比与比例钱币配对与分组

难度评级：960

小提示：

把每个原价气球和一个折扣气球配成一组。

Pair each full-price balloon with its discounted companion

大提示：

两个气球的促销组合花费等于 $\frac53$ 个原价气球。

A two-balloon sale pair costs $\frac53$ regular balloons

解答：

每一对气球的价格是一个气球原价的 $1+\frac23=\frac53$ 倍。

因此，带着刚好够买 $30$ 个原价气球的钱，Orvin 可以买 $30\cdot\frac65=36$ 个气球。

所以正确答案是 C。

Each pair of balloons costs $1+\frac23=\frac53$ times the regular price of one balloon.

Thus, with the money for $30$ regular-price balloons, Orvin can buy $30\cdot\frac65=36$ balloons.

Thus, the correct answer is C .

2014 AMC 10B 第 6 题

答案：C

难度评级：960

小提示：

大提示：

解答：

其他年份的第 6 题