This is an SAT prep question. Senai customized her bicycle by exchanging the front wheel for a wheel that had one half the diameter of the back wheel. Now Senai rides the bicycle, how many revolution does the front wheel make for each revolution on the back wheel?
Diameter big wheel = D
diameter little wheel = D/2
In one revolution, the back wheel goes forward pi D
meanwhile the forward wheel also has to go forward pi D, which is 2 pi (D/2)
so the little wheel makes two revolutions for each of thew big wheel