Question

. A motorcyclist drives from A to B with a uniform speed of 30km/h and returns back with a speed of 20km/h. Find its average speed. 



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Answer 1

Answer:

24 km/hr

Explanation:

Lets suppose the time taken in moving from A to B is T1.

Speed = 30km/hr

So T1= AB/30

 

Lets suppose the time taken in moving from B to A is T2

Speed = 20 km/hr

T2 = AB/20

 

Total distance = 2AB

Total Time = AB/20 + AB/30

= AB [1/20 +1/30]

= AB [50/600]

=AB x 5/60

 

Average Speed = Total Distance / Total Time

= 2AB x 60/AB x 5 = 120/5 = 24 km/hr

Answer 2

Explanation:

LET'S SUPPOSE TIME TAKEN A to B is T1

SPEED = 30km/ h

SO TIME TAKEN ( T1) = AB/30

LET'S SUPPOSE THE TIME TAKEN B to A is T2

SPEED= 20km/h

NOW, TIME TAKEN ( T2) =AB/20

TOTAL DISTANCE = 2AB

TOTAL TIME TAKEN =AB/30 + AB/20

= (2AB+3AB)/60

= 5AB/60

AVERAGE SPEED

=TOTAL DISTANCE TRAVELLED

/ TOTAL TIME TAKEN

=. 2AB *60 / 5 AB

=. 2*12km

=24Km