Question

在最近一场篮球比赛中，Shenille 只投三分球和两分球。她三分球命中率为 $20\%$ ，两分球命中率为 $30\%$ 。Shenille 共出手 $30$ 次。她得了多少分？

In a recent basketball game, Shenille attempted only three-point shots and two-point shots. She was successful on $20\%$ of her three-point shots and $30\%$ of her two-point shots. Shenille attempted $30$ shots. How many points did she score?

$12$

$18$

$24$

$30$

$36$

答案：B

知识点：百分数一次方程

难度评级：1020

小提示：

设两分球和三分球出手数分别为 $x$ 和 $y$ 。

Let $x$ and $y$ be the numbers of two-point and three-point attempts

大提示：

计算每种出手平均贡献多少分。

Compare the points earned per attempted shot type after applying the success percentages

解答：

设两分球出手 $x$ 次，三分球出手 $y$ 次。

那么 Shenille 命中 $0.3x$ 个两分球和 $0.2y$ 个三分球，总得分为 $2 \cdot 0.3x + 3 \cdot 0.2y = 0.6x + 0.6y\text{。}$

我们知道 $x + y = 30$ $0.6(x + y) = 18\text{。}$

所以正确答案是 B。

Let $x$ be the number of two-point shots and $y$ be the number of three-point shots.

Then, Shenille makes $0.3x$ two-point shots and $0.2y$ three-point shots, for a total score of $2 \cdot 0.3x + 3 \cdot 0.2y = 0.6x + 0.6y.$

We know that $x + y = 30$ $0.6(x + y) = 18.$

Thus, B is the correct answer.

2013 AMC 10A 第 9 题

答案：B

难度评级：1020

小提示：

大提示：

解答：

其他年份的第 9 题