Wang Hua has three ropes. The lengths of these three ropes are 7 meters, 11 meters and 15 meters respectively. What is the average length of these three ropes?
王华有三根绳子．分别长7米、11米、15米，这三根绳的平均长度是多少？
<gadget id="calculator">7 + 11 + 15</gadget>
<output>33</output>

<gadget id="calculator">33 / 3</gadget>
<output>11</output>

<result>11</result>