There are 2 red balls, 3 white balls, and 5 yellow balls in the pocket. If you can only touch 1 ball at a time, what is the probability of touching the red ball for the first time? (fill in the simplest fraction)
口袋中装有红球2个，白球3个，黄球5个，如果每次只能摸1个球，第l次摸到红球的可能性是多少．(填最简分数)
<gadget id="calculator">2 / 10</gadget>
<output>1/5 = around 0.2</output>

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