Question

Rishi covers a distance first 30 minutes with 40kmph next 45 minutes with 60 kmph and 2 hrs with 70 kmph . Find the average speed.

Answer 1

average speed = total distance/total time
we know,
distance = speed × time

Rishi covers total distance = distance covers in 30min with 40km/h + distance covers in next 45 min with speed 60 km/h + next 2 hours with speed 70 km/h

total distance = {30/60 hr}{40} +{45/60hr}{60} +{ 2hrs}{70}

= 20 km + 45 km + 140 km
= 205 km

total time taken by Rishi = 30min + 45min + 2 hrs = (1/2 + 3/4 + 2) hrs = 13/4 hrs

now,
Rishi's average speed = ( 205)/(13/4)
= 205×4/13 = 15.77×4 =63.08 km/h

Answer 2

here is the solution....!!!!