There are five numbers, and their average is 12.5. If these five numbers are arranged in ascending order, the average of the first three numbers is 11.6, the average of the last three numbers is 13.5, and the middle number is How many.
有五个数，它们的平均数是12.5，如果将这五个数按从小到大的顺序排，前三个数的平均数是11.6，后三个数的平均数是13.5，中间的数是多少．
<gadget id="calculator">11.6 * 3</gadget>
<output>34.8</output>

<gadget id="calculator">13.5 * 3</gadget>
<output>40.5</output>

<gadget id="calculator">12.5 * 5</gadget>
<output>62.5</output>

<gadget id="calculator">40.5 - 62.5</gadget>
<output>-22</output>

<gadget id="calculator">34.8 + (-22)</gadget>
<output>12.8</output>

<result>12.8</result>