One first prize, eight second prizes, 30 third prizes, and 100 encouragement prizes were placed in a lottery box. So what are the chances of getting the third prize?
一个抽奖箱里放了1个一等奖，8个二等奖，30个三等奖，100个鼓励奖．那么摸到三等奖的可能性是多少
<gadget id="calculator">1 + 8 + 30 + 100</gadget>
<output>139</output>

<gadget id="calculator">30 / 139</gadget>
<output>30/139 = around 0.215827</output>

<result>30/139 = around 0.215827</result>