Math, asked by nancy2738, 11 months ago

A motorist travels to a place 150km away at an average speed of 50km per hour and returns at 30km per hour. His average speed for whole journey in km per hour is?

Answers

Answered by harshitha006

avg speed=2xy/x+y
2×50×30/50+30
3000/80
300/8
150/4
75/2
37.5kmph is answer obtained

amarjithraveendran: Avg speed=total distance / total time
total distance=300km
time=distance/speed
time at 1st half=150/50
time at 2nd half=150/30
total time=150/50+150/30
Avg speed =300/150/50+150/30=300×1500/12000
answer=37.5km/h

harshitha006: those are old and longest methods better get update with new techniques

amarjithraveendran: sure i will try it next time

amarjithraveendran: but will i get full Marks in exam

harshitha006: yes it's the latest method which is following by many books

Answered by sk940178

The average speed of the motorist is 37.5 km/hr.

Step-by-step explanation:

A motorist travels a distance of 150 km and comes back. He goes with an average speed of 50 km per hour and comes back with a speed of 30 km per hour.

Now, the total time taken by the motorist for this return trip is $(\frac{150}{50} + \frac{150}{30}) = 3 + 5 = 8$ hours.

And the total distance traveled by the motorist is (150 + 150) = 300 km.

Therefore, the average speed of the whole journey in km per hour will be

= $\frac{\textrm {Total distance Traveled}}{\textrm {Total time taken}}$

= $\frac{300}{8} = 37.5$ km per hour. (Answer)

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