Subject: General Aptitude · Chapter: Problems on Trains · Exam: · Marks: · Difficulty:
A 270 m long train running at the speed of 120 kmph crosses another train running in opposite direction at the speed of 80 kmph in 9 seconds. What is the length of the other train?
(a)230 m
(b)240 m
(c)260 m
(d)320 m
(e)None of these
Answer
Answer (as printed): A
Explanation
Relative speed $=(120+80) \mathrm{km} / \mathrm{hr}$ $$=\left(200 \times \frac{5}{18}\right) \mathrm{m} / \mathrm{sec}=\left(\frac{500}{9}\right) \mathrm{m} / \mathrm{sec} .$$ Let the length of the other train be $x$ metres. Then, $\frac{x+270}{9}=\frac{500}{9}$ $$\Leftrightarrow x+270=500 \Leftrightarrow x=230 .$$
Explanation as extracted from the printed page; notation may be imperfect.