Subject: General Aptitude · Chapter: Problems on Trains · Exam: 2010 · Marks: · Difficulty:
A train, 240 m long, crosses a man walking along the line in opposite direction at the rate of 3 kmph in 10 seconds. The speed of the train is
(a)63 kmph
(b)75 kmph
(c)83.4 kmph
(d)86.4 kmph
Answer
Answer (as printed): C
Explanation
Speed of the train relative to man $=\left(\frac{240}{10}\right) \mathrm{m} / \mathrm{sec}=24$ $$\mathrm{m} / \mathrm{sec}=\left(24 \times \frac{18}{5}\right) \mathrm{km} / \mathrm{hr}=\frac{432}{5} \mathrm{km} / \mathrm{hr} .$$ Let the speed of the train be $x \mathrm{kmph}$. Then, relative speed $=(x+3) \mathrm{kmph}$. $$\therefore x+3=\frac{432}{5} \Leftrightarrow x=\frac{432}{5}-3=\frac{417}{5}=83.4 \mathrm{kmph} .$$