A railway engine passes two bridges of lengths 400 m and 235 m in 100 seconds and 60 seconds, respectively. Twice the length of the railway engine (in m) is:
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 25
Given:
Length of the two bridges are 400 m and 235 m
Time taken to cover the two bridges = 100 sec and 60 sec
Concept Used:
Speed = Distance/Time
When a train covers a bridge then it will cover the length of its own and the length of that bridge.
Explanation:
Let the length of the engine be X m.
According to the question -
(400 + X)/100 = (235 + X)/60
⇒ (400 + X)/5 = (235 + X)/3
⇒ 1200 + 3X = 1175 + 5X
⇒ 1200 - 1175 = 5X - 3X
⇒ 2X = 25
⇒ X = 25/2
Length of the engine = 25/2 m
Hence two times the length of the engine = (25/2) × 2 = 25 m