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A train is moving with uniform speed crosses two tunnels of lengths 270 metres and 450 metres in 12 seconds and 15 seconds respectively. What is the speed (in km/hr) of the train?
- A144
- B169
- C196
- D216
Answer not set
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CCommunity
Let length of the train be L meters and speed of the train be x km/h
According to the question,
(L + 270)/12 = (L + 450)/15
⇒ (L + 270)/4 = (L + 450)/5
⇒ 5L + 1350 = 4L + 1800
⇒ L = 450
Thus, speed of the train = (450 + 270)/12 = 720/12 = 60 m/s = 60 × 18/5 = 216 km/h
According to the question,
(L + 270)/12 = (L + 450)/15
⇒ (L + 270)/4 = (L + 450)/5
⇒ 5L + 1350 = 4L + 1800
⇒ L = 450
Thus, speed of the train = (450 + 270)/12 = 720/12 = 60 m/s = 60 × 18/5 = 216 km/h