Question

A car is moves 30 km. in 30 min. and the next 30 km. in 40 min. calculate the average speed for the entire journey.

Answer 1

average speed =total distance covered /total time taken

 1.speed of car=30km/h

time taken=30 minutes 

In hour=30/60

=1/2hour

distance=speed *time

=30*1/2

=15km

2.Next the speed of car=30km/h

time taken=40 min

In hour=40/60

=2/3hour

distance = 30*2/3

=20km

Average speed=total distance covered /total time taken

so,20+15/1/2+2/3

=35/7/6

=35*6/7

=210/7

=30km/h

hence  average speed of car is 30km/h

hope it helps!!!!!!

Answer 2

a car move 30km in 30 min mean 1/2h
next it move 30km in 40 min mean 2/3h
average speed=total distance/total time
=30+30/1/2+2/3
=60/7/6
60×6/7
=360/7
=51.4km/h