Question

A train travels at the speed of 60 km/h for 0.5h, at 30 km/h for the next 0.2 h and then at 70km/h for the next 0.7h. What is the average speed of the train?? pls answer it

Answer 1

Given 
v1 = 60 km/h
t1 = 0.5 h
s1 = 60 * 0.5 = 30 km 

v2 = 24
t2 = 0.25 h
s2 = 24 * 0.25 = 6 km

v3 = 72 km/h
t3 = 0.75 h
s3 = 72 * 0.75 = 54 km

hence total distance - 30 + 6 + 54 = 90 km
hence average speed = ?
tot. time = 0.5 + 0.25 + 0.75 = 1.5 h 
ave. speed = distance / time
= 90 / 1.5
= 60 km/h


:) Hope this will help you.