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题库 / Prep2007E1-PS-51
Circular gears P andQ start rotating at the same time at constant speeds. Gear P makes 10 revolutions per minute, andgear Q makes 40 revolutions per minute. How many seconds after the gears start rotating will gear Q have madeexactly 6 more revolutions than gear P ?
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t/y=60/40，t/x=60/10，y-x=6； 或t=p*6=(p+6)*1.5