Now there are balls of the same size in the pocket, 3 white balls, 9 yellow balls, and 3 red balls. If you draw a ball randomly, what is the probability of getting a white ball?
现口袋里有大小相同的球，白球3个，黄球9个，红球3个，从中任意摸出一个球，摸到白球的可能性是多少．
<gadget id="calculator">3 + 9 + 3</gadget>
<output>15</output>

<gadget id="calculator">3 / 15</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>