The diameter of a wheel is 70 cm. It completes 600 revolutions in 1 minute. The speed, in km/h, of the vehicle is:(Take $$\pi = \frac{22}{7}$$)

We know, 

Distance covered in 1 revolution = circumference of the wheel 

As we know, 

Circumference of circular wheel = $$2\pi\ r$$ = $$2\times\ \frac{22}{7}\times\ 35=220$$

Distance covered in 1 min = $$220\times\ 600=132000$$ = 1.32 km

Distance covered in 1 hr = $$1.32\times\ 60=79.2\ km$$

As we know, Distance covered in 1 km = speed per km

speed of the vehicle = 79.2 km/hr 

Hence, Option B is correct.