Speed of ram while travelling from point A to point B is 50 km/hr and while returning he decreased his speed by 40%. Find his average speed of whole journey.
Speed of ram while travelling from point A to point B is 50 km/hr and while returning he decreased his speed by 40%. Find his average speed of whole journey.
A33.33 km/hr
B35.75 km/hr
C42.55 km/hr
D37.5 km/hr
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correct answer is: option d) [37.5 km/hr]
Explanation: Let the distance between point A and point B be D km.
Time taken from A to B = D/50 hours.
Ram decreased his speed by 40% while returning. So, his return speed is 50 - (40/100)*50 = 50 - 20 = 30 km/hr.
Time taken from B to A = D/30 hours.
Total distance travelled = D + D = 2D km.
Total time taken = D/50 + D/30 = (3D + 5D)/150 = 8D/150 = 4D/75 hours.
Average speed = Total distance / Total time = 2D / (4D/75) = (2D * 75) / 4D = 150/4 = 37.5 km/hr. which results in 37.5 km/hr.
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