Question

一个袋子里只有蓝球和绿球。袋中有 $6$ 个蓝球。如果从袋中随机取出一个球，取到蓝球的概率是 $\dfrac14$ ，那么袋中有多少个绿球？

A bag contains only blue balls and green balls. There are $6$ blue balls. If the probability of drawing a blue ball at random from this bag is $\dfrac14,$ then the number of green balls in the bag is

$12$

$18$

$24$

$30$

$36$

答案：B

知识点：基本概率比与比例

难度评级：860

解答：

蓝球占袋中球总数的 $\dfrac14$ ，而蓝球有 $6$ 个，所以总数是 $6 \cdot 4 = 24$ 个。

绿球数为 $24 - 6 = 18$ 。

所以正确答案是 B。

Since blue balls make up $\dfrac14$ of the bag and there are $6$ of them, the total is $6 \cdot 4 = 24$ balls.

So the number of green balls is $24 - 6 = 18$ .

Thus, the correct answer is B .

1990 AMC 8 第 14 题

答案：B

难度评级：860

解答：

其他年份的第 14 题