What is the median of a set of data 15, 25, 30, 18, 22, 27, 19, 21?
一组数据15、25、30、18、22、27、19、21的中位数是多少．
<gadget id="calculator">21 + 22</gadget>
<output>43</output>

<gadget id="calculator">43 / 2</gadget>
<output>43/2 = around 21.5</output>

<result>43/2 = around 21.5</result>