bicycle and a moped travel the same distance. The bicycle wheel turns 350 revolutions. It is known that the outer diameter of the bicycle tire is 7.2 decimeters, and the outer diameter of the moped tire is 4.2 decimeters. How many revolutions did the moped turn?
一自行车和一助动车走过同一段路程，自行车车轮转了350转，已知自行车轮胎外直径为7.2分米，助动车轮胎外直径为4.2分米，求助动车转了多少转？
<gadget id="calculator">3.14 * 7.2 * 350</gadget>
<output>7_912.8</output>

<gadget id="calculator">3.14 * 4.2</gadget>
<output>13.188</output>

<gadget id="calculator">7_912.8 / 13.188</gadget>
<output>600</output>

<result>600</result>