Question

Only a single rail track exists between station A and B on a railway line. One hour after the north bound
superfast train N leaves station A for station B, a south passenger train S reaches station A from station B.
The speed of the superfast train is twice that of a normal express train E, while the speed of a passenger
train S is half that of E. On a particular day N leaves for station B from station A, 20 minutes behind the
normal schedule. In order to maintain the schedule both N and S increased their speed. If the superfast
train doubles its speed, what should be the ratio (approximately) of the speed of passenger train to that of
the superfast train so that passenger train S reaches exactly at the scheduled time at the station A on that
day.
(1) 1 : 3 (2) 1 : 4 (3) 1 : 5 (4) 1 : 6

Answer 1

Answer:

As per condition , initial ratio of the speed of passenger train to that of the super fast train is 1:4.

Initially, passenger train takes 4/5 or 48 mins hr to travel from B to A and superfast train train takes 1/5 hr or 12 mins to reach stn A from Stn B.

when On a particular day N leaves for station B from

Station A, 20 minutes behind the normal schedule. In order to maintain the schedule both N and S increased their speed. If the super fast train doubles its speed, it covers distance in 6 mins and remains 14 mins behind schedule.

to maintain schedule, passenger train has to cover the distance in 48-14 = 34 mins.

so final ratio of speeds will be 6:34 or 1:6 (approx.)

so answer is option 4 which is 1:6