The radius of the wheel of a bus is 70 cms and the speed of the bus is 66 km/h, then the r.p.m. (revolutions per minutes)of the wheel is	Pick:
A) 200
B) 250
C) 300
D) 330
E) None of these
Radius of the wheel of bus = 70 cm. Then,   circumference of wheel = 2πr = 140π = 440 cm   Distance covered by bus in 1 minute   = 66⁄60 × 1000 × 100 cms   Distance covered by one revolution of wheel   = circumference of wheel   = 440 cm   ∴ Revolutions per minute = 6600000/60×440 = 250   Answer 250
<result>B</result>
The radius of the wheel of a bus is 70 cms and the speed of the bus is 66 km/h, then the r.p.m. (revolutions per minutes)of the wheel is