Question

a car travels the first 50 km of its journey at an average speed of 25 km/h and the next 120 km at an average speed of 80 km /h. The car complete the last part of it's journey at an average speed of 90 km/hr in 35 mins. Find the average speed of it's entire journey. Giving ur ans in km/h
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Answer 1

Answer:

A car travels the first 50km of its journey at an average speed of 25m/s.

25m/s = 25*3600/1000 = 90 km/ hr.

Time = Distance/speed

Time = 50/90

=5/9hr.

next 120 km at an average speed of 80km/hr.

=Time = 120/80

=3/2h

last part of its journey at an average speed of 90km/hr in 35mins.

Time = 35 mins.

=35/60hr

=7/12hr.

Distance covered = 9*7/12=105/2km.

Total distance = 50+120+105 /2 =435/2km.

Total time = 5/9+3/2+7/12 =(20+54+21) /36

=95/36.

Average speed=

(435/2) /(95/96) =

432*18/95

=81.85km/hr.

thanks