Question

A bus goes to ranchi from patna at the rate of 60 km per hour. Another bus leaves ranchi for patna at the same times as the first bus at the rate of 70 km per hour. Find the average speed for the journeys of the two buses combined if it is known that the distance from ranchi to patna is 420 kilometers.

Answer 1

Answer:

Average speed=64.61 km/hr.

Explanation:

Since we know the distance between the ranchi and patna is 420 km.

First bus travel with a speed of 60 km/hr

we know that $speed=\frac{distance}{time}$

So,$60=\frac{420}{t}$

So,t=7 hours

That means first bus takes 7 hours to travel from ranchi to patna.

Second bus travel with a speed of 70 km/hr

So,$70=\frac{420}{t}$

So,t=6 hours.

That means second bus takes 6 hours to travel from ranchi to patna.

we know that $average speed=\frac{Total\ distance}{Total\ time}$..........(1)

So,$average speed=\frac{420+420}{7+6}$=$\frac{840}{13}$=64.61

So, average speed=64.61 km/hr.