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Bunuel
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Bunuel
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seems like a 700 level problem, not sub-600.
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The question is absolutely 700 level. Great Language trap.
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I have edited the question and the solution by adding more details to enhance its clarity. I hope it is now easier to understand.
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KarishmaB
Hmmmm....I got into a trap.
30/3600 = 1/120 h

so we have:
1/30h 4km 120 km/h -> 1/60h 2km 120km/h

1/120 + 1/30 h -> 1/40h. It's the time with 30 additional seconds.

Then 1/40 * x = 2 -> x - 80 km/h

Where did I make a mistake?
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MBAToronto2024
KarishmaB
Hmmmm....I got into a trap.
30/3600 = 1/120 h

so we have:
1/30h 4km 120 km/h -> 1/60h 2km 120km/h

1/120 + 1/30 h -> 1/40h. It's the time with 30 additional seconds.

Then 1/40 * x = 2 -> x - 80 km/h

Where did I make a mistake?

I am not sure what and how you did there. Note that the two instances are separate and we might as well have had different trains. The two speeds, time taken and distances are different.

Case 1:
It covers 4 kilometers at a speed of 120 kilometers per hour. Time taken = 4/120 = 1/30 hrs = 2 mins

Case 2:
It takes 30 secs extra to cover 2 kms at another speed.

30 seconds extra means the time taken = 2 mins 30 secs = 2.5 mins

Distance covered = 2 kms

\(Speed = \frac{2}{2.5/60} = 48\) kmph

Answer (C)


Discussion on TSD: https://youtu.be/7ASEIvxYPCM
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I like the solution - it’s helpful.
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phmahi1997
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I like the solution - it’s helpful.
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phmahi1997
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I like the solution - it’s helpful.
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