Given that the average of data 1, 2, x, and 5 is 2.5, what is the median of this group of data?
已知数据1，2，x，5的平均数为2.5，则这组数据的中位数是多少．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

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

<gadget id="calculator">5 / 4</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">2.5 - (1/4) - (1/2) - (5/4)</gadget>
<output>0.5</output>

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

<result>2</result>