Discussion

Explanation:

Case 1: Train 2 starts 2 hours after Train 1.
Train 1 travels from 12 pm till 8 pm i.e., for 8 hours.
Same distance is travelled by Train 2 from 2 pm till 8 pm i.e., in 6 hours.
∴ Ratio of speeds of Train 1 and Train 2 = 6 : 8 = 3 : 4
⇒ Let speed of Train 1 = 3x and Train 2 = 4x
⇒ 3x + 4x = 140
⇒ x = 20

⇒ Speed of Train 1 = 60 kmph, Speed of Train 2 = 80 kmph.

Case 2: Train 2 starts 5 hours after Train 1.
Train 1 would have travelled 5 × 60 = 300 kms when Train 2 starts i.e., at 5 pm.
Relative speed of the two trains = 80 - 60 = 20 kmph.
∴ Time for Train 2 after it starts to meet Train 1 = 300/20 = 15 hours.

⇒ 15 hours after 5 pm = 8 am the next day.

Hence, option (c).

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Doubts


riddhime said (2023-06-14 10:15:21)

A train left point A at 12 noon. Two hours later, another train started from point A in the same direction. It overtook the first train at 8 PM. It is known that the sum of the speeds of the two trains is 140 km/hr. Then, at what time would the second train overtake the first train, if instead the second train had started from point A in the same direction 5 hours after the first train? Assume that both the trains travel at constant speeds.

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Solution updated.


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