two gears are meshed. the first gear has 20 teeth per inch and is rotating at 500 rpms. what is the speed of the second gear if it has 40 teeth per inch?

Question

possible answers: A. 500  B. 400  C. 250  D. 200

 

i did cross multiplication and got 1000! Answer key says C. 250 is the correct answer. 

 

I did :

 

20/500=40/x 

20000=20x

x=1000

Answer 1

The ration is inverse, not direct. The bigger the wheel the slower it revolves.

 

(20)(500) = (40)(s)

250 = s