What is the average of the data 13, 19, 21, 28, 30, 30, 35, 40, 41, 41, 41, 42.
数据13，19，21，28，30，30，35，40，41，41，41，42的平均数是多少．
<gadget id="calculator">13 + 19 + 21 + 28 + 30 + 30 + 35 + 40 + 41 + 41 + 41 + 42</gadget>
<output>381</output>

<gadget id="calculator">381 / 12</gadget>
<output>127/4 = around 31.75</output>

<result>127/4 = around 31.75</result>