Question

A train travels from A to B with speed 20 km/hrs and from B to A with speed 30 km/hrs.
Average speed (in km/hrs) of the train for the whole journey is

Answer 1

Answer: 24 km/h

Step-by-step explanation:

Since we know that,

Time = Distance/Speed

Taking time taken from A to B as t

t = d/20

Taking time taken from B to A as t'

t' = d/30

Here d will remain same since distance between A and B is same.

Average speed = Total distance/Total time

Average speed = ( d + d )/( d/20 + d/30 )

= 2d/( 3d + 2d )/60

= 2d/5d × 60

= 2 × 12 = 24 km/h

Answer 2

Hello!

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We knwo that,

Time = Distance/speed

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Suppose time from A to B is X

X = D/20

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Suppose time from A To B is xy

xy =D/30

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We know that,

Average speed = Total distance/Total time

Therefore,

Average speed = ( d + d )/( d/20 + d/30 )

2d/( 3d + 2d )/60

= 2d/5d * 60

= 2 *12 = 24 km/h

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Therefore,

Answer = 24km/h

$24km$