Two trains, each 550 m long, moving in opposite directions, cross each other…
2025
Two trains, each 550 m long, moving in opposite directions, cross each other in 15 seconds. If one is moving twice as fast the other, then the speed of the faster train is:
- A.
166 km/hr
- B.
168 km/hr
- C.
176 km/hr
- D.
160 km/hr
Attempted by 9 students.
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Correct answer: C
Answer: 176 km/hr
Solution (step-by-step):
Total distance to be covered when the trains pass each other = 550 m + 550 m = 1100 m.
Time taken = 15 s, so relative speed = distance/time = 1100/15 = 73.333... m/s.
Let the slower train's speed be v (m/s). The faster train's speed is 2v, so relative speed = v + 2v = 3v.
Set 3v = 73.333... ⇒ v = 73.333.../3 = 24.444... m/s. Faster train speed = 2v = 48.888... m/s.
Convert to km/hr: multiply m/s by 3.6 ⇒ 48.888... × 3.6 = 176 km/hr.
Therefore the speed of the faster train is 176 km/hr.