an aeroplane flies from A to B @ 500 km/hour and comes back from to B to A @ 700n km/hour. the average speed of the aeroplane is
i) 600 km./hour
ii) 583.33 km./hour
iii) 100 √35 km./hour
iv) 620 km./hour
an aeroplane flies from A to B @ 500 km/hour and comes back from to B to A @ 700n km/hour. the average speed of the aeroplane is
i) 600 km./hour
ii) 583.33 km./hour
iii) 100 √35 km./hour
iv) 620 km./hour
Let distance between A and B is 'X' kms
so, time taken to travel from A to B = 'x' / 500 ( Time = distance / speed)
similarly, time taken to travel from B to A = 'x' / 700 ( Time = distance / speed)
so total distance traveled= x + x = 2x
therefore, speed = distance / time = 2x / [ x /500 + x /700] = 2 / [1/500+ 1/700] = 583.33 kms
Let us assume the distance from A to B to be 3500 Kms. (L.C.M. of 500 & 700)
SPEED DISTANCE TIME
500 Km / Hr. 3500 Kms. 7 Hrs.
700 Km/Hr. 3500 Kms. 5 Hrs.
Total 7000 Kms. 12 Hrs.
Average Speed = Total Distance / Total Time = 7000 Kms / 12 Hrs. = 583.33 Kms. / Hr.
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