Question

Suresh goes from station A to station B at the speed of 40 km per hour and returns from station B to station A at the at the speed of 60 km per hour find his average speed for the whole journey. the best answer given is considered best .

Answer 1

the average speed is 50 km/hr

Answer 2

Let distance from A to B be "x" km
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Time from A to B = x/40 hr
Time from B to A = x/60 hr
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Average speed = (total distance)/(total time)
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= (2x)/(x/40 + x/60)
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= (2x)/[(60x + 40x)/40*60]
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= (2x)/[100x/2400]
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= 2*2400/100
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= 48 kmh