Xiao Ming is red-green color blind, now there are 7 green balls and 4 red balls, what is the possibility that she can correctly point out the red balls.
小明是一个红绿色盲，现在有7个绿球和4个红球，她能正确指出红球的可能性是多少．
<gadget id="calculator">4 + 7</gadget>
<output>11</output>

<gadget id="calculator">4 / 11</gadget>
<output>4/11 = around 0.363636</output>

<result>4/11 = around 0.363636</result>