A small pulley is 13 in. in diameter, and a larger one is 19 in. in diameter. How many rpm does the larger pulley make if the smaller one revolves at 570 rpm?
A) 820 rpm
B) 833.0769230769 rpm
C) 410 rpm
D) 390 rpm
E) 380 rpm

Question

Quizplus · Accepted Answer

The speed of the pulleys is inversely proportional to their diameters. Therefore, if the smaller pulley (13 in.) revolves at 570 rpm, the larger one (19 in.) would revolve at (13/19) * 570 = 390 rpm.

A Small Pulley Is 13 In