ABC26GN3877 · Problems on Trains
Subject: General Aptitude · Chapter: Problems on Trains · Exam: · Marks: · Difficulty:
A train 800 metres long is running at a speed of 78 km/hr. If it crosses a tunnel in 1 minute, then the length of the tunnel (in metres) is :
Answer
Explanation
Speed $=\left(78 \times \frac{5}{18}\right) \mathrm{m} / \mathrm{sec}=\left(\frac{65}{3}\right) \mathrm{m} / \mathrm{sec}$. Time = 1 minute = 60 sec. Let the length of the tunnel be $x$ metres. Then, $\frac{800+x}{60}=\frac{65}{3}$ $$\begin{aligned} & \Leftrightarrow 3(800+x)=3900 \\ & \Leftrightarrow x=500 . \end{aligned}$$
Explanation as extracted from the printed page; notation may be imperfect.
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