Question

One has 60 teeth and it makes 50 complete revolutions in a minute. How many complete revolutions will the second gear complete, if it has 40 teeth?

Answer 1

Write and solve the equation of 2 ratios:

   60 teeth       50 rev
-------------- = -------------
   40 teeth          x

x= 3000/40 = 75

The smaller (40 tooth) gear will make 75 rev in a min.

Answer 2

60/50= 1.2 

1.2= 40x
x=40/1.2 
x=33.3