Question

a man travels from Delhi to Bombay at an average of 30 mph and returns along the same route the average of 60 mph find the average speed of the total trip

Answer 1

Answer:

20 km/hr.

Step-by-step explanation:

Let total journey = y km

Total time taken = time taken during 60% of distance + time taken during 20% of distance + time taken in remaining distance  

= [( 60y / 100 ) / 30] + [( 20y / 100 ) / 20] + [( 20y / 100 ) / 10]

= ( y / 50 + y / 100 + y / 50 )hrs

= y/20 hours.

Average speed = total distance traveled / total time taken.

= [y / ( y/20 )] km/hr

=20 km/hr.

Answer 2

Answer:

Step-by-step explanation:

The easiest way to find out average speed of anything is--->

Let x be the speed during the 1st trip

And y be the speed of during the second trip

So the avg speed is = x*y/(x+y)

Here x=30 and y=60 so avg speed = 60*30/(60+30)

1800/90=20mph