There are 4 table tennis balls in a box, 3 red balls and 1 yellow ball. Xiaoliang touches it three times, and all he touches are red balls (touch one ball each time and put it back into the box). What is the probability that Liang touches the yellow ball for the fourth time?
一个盒子中装着4个乒乓球，红色球3个，黄色球1个，小亮摸了三次，摸到的都是红色球(每次摸一个球再放回盒中)，如果继续摸，小亮第四次摸到黄色球的可能性是多少
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>