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A person travels from A to B at a speed of 40 kmph and returns by increasing his speed by 50%. What is his average speed for both the trips?

A person travels from A to B at a speed of 40 kmph and returns by increasing his speed by 50%. What is his average speed for both the trips?

Explanation

 

Given:

  • Speed from A to B = 40 km/h

  • Speed from B to A = 40 km/h + 50% of 40 km/h = 40 + 20 = 60 km/h

Find:

Average speed for the whole journey (both ways).

Formula for average speed when distance is the same but speeds differ:
Average speed=2×Speed1×Speed2Speed1+Speed2text{Average speed} = frac{2 times text{Speed}_1 times text{Speed}_2}{text{Speed}_1 + text{Speed}_2}

Plug in values:

=2×40×6040+60=4800100=48 km/h= frac{2 times 40 times 60}{40 + 60} = frac{4800}{100} = 48 text{ km/h}=2×40×60​40+60

=4800/100

=48 km/h