Subject: General Aptitude · Chapter: Problems on Trains · Exam: 2007 · Marks: · Difficulty:
A train running at a speed of 90 km/hr crosses a platform double its length in 36 seconds. What is the length of the platform in metres?
(a)200
(b)300
(c)450
(d)Cannot be determined
(e)None of these
Answer
Answer (as printed): E
Explanation
Let the length of the train be $x$ metres. Then, length of the platform $=(2 x)$ metres. Speed of the train $=\left(90 \times \frac{5}{18}\right) \mathrm{m} / \mathrm{sec}=25 \mathrm{m} / \mathrm{sec}$. $$\therefore \frac{x+2 x}{25}=36 \Leftrightarrow 3 x=900 \Leftrightarrow x=300 .$$ Hence, length of platform $=2 x=(2 \times 300) \mathrm{m}=600 \mathrm{m}$.