There are 5 red balls, 4 white balls and 3 black balls in a pocket. If you touch it once, what is the probability of getting a white ball?
一个口袋中装有5个红球、4个白球和3黑球，如果给你摸一次，摸到白球的可能性是多少．
<gadget id="calculator">5 + 4 + 3</gadget>
<output>12</output>

<gadget id="calculator">4 / 12</gadget>
<output>1/3 = around 0.333333</output>

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