Select 4 students from 6 students to participate in the knowledge competition, what is the probability that A is selected?
从6名学生中选4人参加知识竞赛，其中甲被选中的概率为多少．
<gadget id="calculator">4 / 6</gadget>
<output>2/3 = around 0.666667</output>

<result>2/3 = around 0.666667</result>