There are 2 red balls and 2 white balls in a sealed opaque bag. Lulu stretches out her hand to grab a ball at random. What is the probability of catching a red ball?
在一个密封的不透明的袋子里装了2个红球、2个白球，露露伸手任意抓1个球，抓到红球的可能性是多少
<gadget id="calculator">2 + 2</gadget>
<output>4</output>

<gadget id="calculator">2 / 4</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>