A bicycle has two wheels (one large and one small) of 120 cm and 40 cm in diameters. When the large wheel makes 10 revolutions, how many revolutions does the small wheel make in that time?

A 15

B 20

C 30

D 40

Correct Answer: Option C

First wheel goes in 1 revolution 2πr = 2πX120/2 = 120π cm

in 10 revolutions it will go 1200π cm

So, Second wheel will also go this distance.

It's radius, r1 = 40/2 =20cm and it goes 2π.20 cm = 40π cm in 1 revolution

So revolutions taken to go this distance = 1200π/40π = 30