Question

The number of revolutions of two pulleys is inversely proportional to their diameters. If a 24-inch diameter pulley making 400 revolutions per minute is belted to an 8-inch diameter pulley, find the number of revolutions per minute of the smaller pulley.
133 1/3
800
1,200 ...?

Answer 1

The correct answer is 1200.

Answer 2

Answer;

1200

Explanation;

• Since diameter (d) is inversely proportional to the revolutions (n) are

Then; dn=k  

We can use the relationship to find the unknown, k:  

k = dn  

k = (24)(400) = 9600  

Then use k to find the unknown n:  

k= dn  

9600 = 8n  

n = 1200  

= 200 rpm