A box contains red and yellow balls of the same size, 3 red balls and 6 yellow balls. If you touch a ball at random, what is the probability of getting a red ball?
箱子里装有大小相同的红、黄两种颜色的球，红球3个，黄球6个．任意摸一个球，摸到红球的可能性是多少
<gadget id="calculator">3 + 6</gadget>
<output>9</output>

<gadget id="calculator">3 / 9</gadget>
<output>1/3 = around 0.333333</output>

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