Problems on Trains Quiz Set 014

The total distance is equal to the sum of the lengths of the trains, so s = 328. This distance has to be covered at a net relative speed equal to the sums of the speeds of the two trains, so v = 82. The time will be distance/speed = $328/82$ = 4 sec.

Let the speed of the train be v km/h. Distance travelled by this train in (6 + 18) hours = 24v km. Equating this to the distance travelled by the second train we get 24v = 8 × 6, which gives v = 2 km/h.

The total distance is equal to the sum of the lengths of the trains, so s = 332. This distance has to be covered at a net relative speed equal to the difference of the speeds of the two trains, so v = 83. The time will be distance/speed = $332/83$ = 4s.

Let the speed of the train be v km/h. Length of the train calculated with the data for the first man = $(v - 4) × 6$. It should equal the length obtained from the data for the second man. So $(v - 4) × 6$ = $(v - 11) × 7$. Please note that we have not converted seconds to hours because that factor will ultimately cancel away. Solving for v we get 53km/h.

The distance to be covered is equal to the length of the train, so s = 936. This distance has to be covered at a net relative speed equal to the sums of the speeds of the man and the train, so v = 72 + 84 = 156. The time will be distance/speed = $936/156$ = 6 s.