There are 2 red balls, 1 yellow ball and 1 black ball in an opaque bag, and these balls are exactly the same in shape, size, texture, etc. If a ball is randomly drawn from the bag, what is the probability of drawing a yellow ball
在一个不透明的袋子中装有2个红球、l个黄球和l个黑球，这些球的形状、大小、质地等完全相同．若从袋子里任意摸出1个球，则摸出黄球的可能性是多少
<gadget id="calculator">2 + 1 + 1</gadget>
<output>4</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>