Question

Two trains $140$ m and $160$ m long run at the speed of $60$ km/hr and $40$ km/hr, respectively, in opposite directions on parallel tracks. What is the time (in seconds) which they take to cross each other?

• A. $10.8$ seconds
• B. $11.2$ seconds
• C. $9.6$ seconds
• D. $10.4$ seconds

Answer 1

Answer: (A)

$10.8$ seconds

Required time $=\frac{\text{Total distance}}{\text{Relative speed}}=\frac{\text{Sum of the lengths of the two trains}}{\text{Sum of speeds}}$
$=\frac{(140+160)\times 18}{(60+40)\times 5}$ seconds $=\frac{300\times 18}{100\times 5}=10.8$ seconds