A train travelling with uniform speed crosses two bridges of lengths 600 m and 900 m in 45 seconds and 60 seconds respectively. What is the speed of the train? एक ट्रेन एकसमान चाल से चलते हुए 600 मी. और 900 मी. लम्बे पुल को क्रमश: 45 सेकेण्ड और 60 सेकेण्ड में पार करती है। ट्रेन की चाल कितनी है ?
-
36 km/hr / किमी./ घंटा
-
54 km/hr / किमी./ घंटा
-
72 km/hr / किमी./ घंटा
-
48 km/hr / किमी./ घंटा
C
Correct answer
Explanation
The train's speed can be found by noting that in the additional 15 seconds (60-45), it travels the extra 300 meters of bridge length (900-600). This gives speed = 300/15 = 20 m/s. Converting to km/hr: 20 × 18/5 = 72 km/hr. Alternatively, total distance = 1500m in 105 seconds, giving the same result.