Put 2 red balls and 2 white balls in a cloth bag, and touch 2 balls at a time, what is the probability that both balls are red?
在布袋里放2个红球，2个白球，一次摸二个球，摸到都是红球的可能性是多少
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<result>1/6 = around 0.166667</result>