The 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 :
Answer & explanation
Correct answer: option 2
Let us assume the length of the engine is = x m
Part1 (Bridge is 400 m long)
Speed of engine = c= 4 m/sec
Part 2 (Bridge is 235 m long)
Speed of engine = \(\frac{235+x }{60}\)
Since the speed of the engine is constant, both the speeds should be equal
\(\frac{400+x }{100}\) = \(\frac{235+x }{60}\)
Solving for x we get-
2400 + 6x = 2350 + 10x
4x = 50
x = 12.5
Twice the length of engine = 2 × 12.5 = 25 m
Twice the length of engine is 25m