A cuboid pool is 20 meters long and 6 meters wide. The water depth in the pool is 1.57 meters. There is a water outlet pipe at the bottom of the pool with an inner diameter of 2 decimeters. When the water is released, the average speed of the water flow is 2 meters per second. How many minutes does it take to empty the pool?
一个长方体水池，长20米，宽6米，池中水深1.57米，池底有根出水管，内直径长2分米．放水时，水流速度平均为每秒流2米．放完池中的水需要多少分钟？
<gadget id="calculator">20 * 6 * 1.57</gadget>
<output>188.4</output>

<gadget id="calculator">0.2 / 2</gadget>
<output>0.1</output>

<gadget id="calculator">0.1 ** 2</gadget>
<output>0.01</output>

<gadget id="calculator">3.14 * 0.01 * 2 * 60</gadget>
<output>3.768</output>

<gadget id="calculator">188.4 / 3.768</gadget>
<output>50</output>

<result>50</result>