There are 7 red balls, 4 yellow balls and 3 white balls in a box, what is the probability of drawing yellow balls?
一个盒子里有7个红球，4个黄球，3个白球，抽到黄求的可能性是多少．
<gadget id="calculator">7 + 4 + 3</gadget>
<output>14</output>

<gadget id="calculator">4 / 14</gadget>
<output>2/7 = around 0.285714</output>

<result>2/7 = around 0.285714</result>