AMC 8 1990 Problem 14

AMC8 1990 年第 14 题

概率★★★☆☆

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

\displaystyle \frac{1}{4}

, then the number of green balls in the bag is

一个袋子里只有蓝球和绿球。有 6 个蓝球。如果从袋中随机抽到蓝球的概率是

\displaystyle \frac{1}{4}

，则袋中绿球的数量是

正确答案 · Correct Answer

解析 · Solution

Solution 1

Since

\displaystyle \frac{1}{4}

of the balls are blue, there are 4×6=24 total balls. Thus 24-6=18 balls are green.

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