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Bunuel
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Distance between two stations A and B is 778 km. A train covers the jo 21 Feb 2019, 00:20
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70% (02:18) correct 30% (02:54) wrong based on 262 sessions

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Distance between two stations A and B is 778 km. A train covers the journey from A to B at 84 km per hour and returns back to A with a uniform speed of 56km per hour. Find the average speed of the train during the whole

A. 66.5 km/hr
B. 67.2 km/hr
C. 67.7 km/hr
D. 68.6 km/hr
D. 68.9 km/hr
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B
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Distance between two stations A and B is 778 km. A train covers the jo 21 Feb 2019, 02:28
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Bunuel
Distance between two stations A and B is 778 km. A train covers the journey from A to B at 84 km per hour and returns back to A with a uniform speed of 56km per hour. Find the average speed of the train during the whole

A. 66.5 km/hr
B. 67.2 km/hr
C. 67.7 km/hr
D. 68.6 km/hr
D. 68.9 km/hr
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Average speed :

2xy / x + y

= 2* 84 * 56 / 140

= 67.2.

B is the correct answer.
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Distance between two stations A and B is 778 km. A train covers the jo 21 Feb 2019, 08:28
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Bunuel
Distance between two stations A and B is 778 km. A train covers the journey from A to B at 84 km per hour and returns back to A with a uniform speed of 56km per hour. Find the average speed of the train during the whole

A. 66.5 km/hr
B. 67.2 km/hr
C. 67.7 km/hr
D. 68.6 km/hr
D. 68.9 km/hr
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use avg speed formula ; since distance is same

2*ab/a+b
; 2 * 84*56/140
IMO B 67.2 km/hr
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Distance between two stations A and B is 778 km. A train covers the jo 27 Feb 2019, 10:42
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As distance for either leg is same i.e 778 km, average speed is not dependent on actual distance.
For ease of calculations, assume distance between A-B as 1.

Time A-B: 1/84
Time B-A: 1/56
Time total: 1/84 + 1/56= 140/84*56= 5/84*2
Total distance: 2
Avg Spd: total distance / total time: 2*84*2/5 = 84*8/10= 672/10= 67.2
Ans B
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Distance between two stations A and B is 778 km. A train covers the jo 03 Mar 2019, 08:51
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Shobhit7
As distance for either leg is same i.e 778 km, average speed is not dependent on actual distance.
For ease of calculations, assume distance between A-B as 1.

Time A-B: 1/84
Time B-A: 1/56
Time total: 1/84 + 1/56= 140/84*56= 5/84*2
Total distance: 2
Avg Spd: total distance / total time: 2*84*2/5 = 84*8/10= 672/10= 67.2
Ans B
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I understand logically that average speed is not dependent on distance since it is the same on both legs, however, why does this mean you can equate it to 1? Can you please explain this
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Distance between two stations A and B is 778 km. A train covers the jo 03 Mar 2019, 08:58
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Ish1996
Shobhit7
As distance for either leg is same i.e 778 km, average speed is not dependent on actual distance.
For ease of calculations, assume distance between A-B as 1.

Time A-B: 1/84
Time B-A: 1/56
Time total: 1/84 + 1/56= 140/84*56= 5/84*2
Total distance: 2
Avg Spd: total distance / total time: 2*84*2/5 = 84*8/10= 672/10= 67.2
Ans B

I understand logically that average speed is not dependent on distance since it is the same on both legs, however, why does this mean you can equate it to 1? Can you please explain this
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Just to ease off the calculation.

Posted from my mobile device
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Distance between two stations A and B is 778 km. A train covers the jo 05 Mar 2026, 12:54
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For the average speed where an object travels the same distance at different speeds, we can use the harmonic mean of the speeds, which as an equation is expressed as 2ab/(a+b). Plugging in our numbers we get 2(84)(56)/(54 + 86) = 9408/140 = 67.2 which is our final answer.
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