ABC26GN3891 · Problems on Trains

Subject: General Aptitude · Chapter: Problems on Trains · Exam: 2010 · Marks: · Difficulty:

Two trains of lengths 120 m and 90 m are running with speeds of 80 km/hr and 55 km/hr respectively towards each other on parallel lines. If they are 90 m apart, after how many seconds they will cross each other?

(a)5.6 sec.

(b)7.2 sec.

(c)8 sec.

(d)9 sec .

Answer

Answer (as printed): C

Explanation

Relative speed $=(80+55) \mathrm{km} / \mathrm{hr}=135 \mathrm{km} / \mathrm{hr}$ $$=\left(135 \times \frac{5}{18}\right) \mathrm{m} / \mathrm{sec}=\left(\frac{75}{2}\right) \mathrm{m} / \mathrm{sec} .$$ Distance covered $=(120+90+90) \mathrm{m}=300 \mathrm{m}$. $$\text { Required time }=\left(300 \times \frac{2}{75}\right) \mathrm{sec}=8 \mathrm{sec} .$$

Open in whiteboard · Browse this chapter in the app