Question

Cagney 每 $20$ 秒给一个纸杯蛋糕涂糖霜，Lacey 每 $30$ 秒给一个纸杯蛋糕涂糖霜。两人一起工作， $5$ 分钟内可以给多少个纸杯蛋糕涂糖霜？

Cagney can frost a cupcake every $20$ seconds and Lacey can frost a cupcake every $30$ seconds. Working together, how many cupcakes can they frost in $5$ minutes?

$10$

$15$

$20$

$25$

$30$

答案：D

知识点：速率单位换算

难度评级：880

解答：

$5$ 分钟共有 $300$ 秒。Cagney 给 $\dfrac{300}{20} = 15$ 个纸杯蛋糕涂糖霜，Lacey 给 $\dfrac{300}{30} = 10$ 个纸杯蛋糕涂糖霜。

两人合起来完成 $15 + 10 = 25$ 个纸杯蛋糕。

因此，正确答案是 D。

In $5$ minutes there are $300$ seconds. Cagney frosts $\dfrac{300}{20} = 15$ cupcakes and Lacey frosts $\dfrac{300}{30} = 10$ cupcakes.

Together they frost $15 + 10 = 25$ cupcakes.

Thus, the correct answer is D.

2012 AMC 12A 第 2 题

答案：D

难度评级：880

解答：

其他年份的第 2 题