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Boris Biker entered the Tour de Transylvania with an unusual bicycle whose front wheel is larger than the back.
The radius of the large wheel is 40cm, and the radius of the small wheel is 30cm.
On the first stage of the race the smaller wheel made 120,000 revolutions. How many revolutions did the larger wheel make?
If you liked this problem, here is an NRICH task that challenges you to use similar mathematical ideas.