There are 10 white balls, 5 yellow balls and 2 red balls in a bag. These balls are the same except for their colors. If a ball is drawn from the bag, what is the probability of getting a red ball?
袋子里有10个白球、5个黄球和2个红球，这些球除颜色不同外，其他均一样，若从袋子里摸出一个球来，摸到红球的可能性是多少．
<gadget id="calculator">10 + 5 + 2</gadget>
<output>17</output>

<gadget id="calculator">2 / 17</gadget>
<output>2/17 = around 0.117647</output>

<result>2/17 = around 0.117647</result>