At 9:45 in the morning, a bus departs from the departure station. After half an hour, it travels one-sixth of the total distance. The average speed of the bus during this distance is 15km/h. At 12:00 noon, the bus arrives at the terminal. What is the average speed of the bus traveling in km/h?
上午9点45分，一辆公共汽车从始发站出发，半小时后，行驶了总路程的六分之一，公共汽车在这一段路程的平均速度是15km/h．中午12：00，公共汽车到达终点站．则全程公共汽车行驶的平均速度是多少km/h．
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">0.5 / (1/6) / 2.25</gadget>
<output>1.333333</output>

<gadget id="calculator">15 * 1.333333</gadget>
<output>19.999995</output>

<result>19.999995</result>