There are 2 white balls, 3 red balls, and 4 black balls in a box. If you touch any ball in the box, what is the probability that you will get exactly the red ball?
盒子里有2个白球，3个红球，4个黑球，从中任意摸一个球，正好摸到红球的可能性是多少．
<gadget id="calculator">3 / 9</gadget>
<output>1/3 = around 0.333333</output>

<result>1/3 = around 0.333333</result>