There is only one rail track between stations A and B on a railway line. One hour after the northbound superfast train N leaves station A for station B, the southbound passenger train S reaches station A from station B. The speed of superfast train is twice that of express train E, while the speed of passenger train S is half of that of train E. On some one day train N leaves from station A to station B 20 minutes late than its usual schedule. Both Train N and Train S have increased their speed to maintain the schedule as per the table. If the superfast train doubles its speed, then what should be the ratio (approximately) of the speed of the passenger train to the speed of the superfast train so that the passenger train reaches the station on that day at the exact scheduled time.

There is only one rail track between stations A and B on a railway line. One hour after the northbound superfast train N leaves station A for station B, the southbound passenger train S reaches station A from station B. The speed of superfast train is twice that of express train E, while the speed of passenger train S is half of that of train E. On some one day train N leaves from station A to station B 20 minutes late than its usual schedule. Both Train N and Train S have increased their speed to maintain the schedule as per the table. If the superfast train doubles its speed, then what should be the ratio (approximately) of the speed of the passenger train to the speed of the superfast train so that the passenger train reaches the station on that day at the exact scheduled time. Correct Answer 3 : 17

Given: 

Ratio of the speeds of train N, E and S = 4 : 2 : 1

Formula used:

Speed = Distance/Time

Assumptions:

Let the time taken by N and S to reach the destination points B and A  is 12 minutes and 48 minutes respectively.

We assume the total distance from A to B be 48 m 

The speed of N and S be 4 m/minute and 1 m/minute 

Let the starting time be 9am 

Calculation:

New speed of N = 8 m/minute 

Time taken from A to B = 48/8 = 6 minutes 

N leaves at 9:20 am and reaches at B at 9:26 am 

So, new speed of S = 48/34 = 24/17 m/minute

Ratio of speed of S and N = 24/17 : 8 

⇒ 3 : 17 

⇒ 3  : 17 

Note∶ The question options was incorrect in the official paper. However, we have changed it and update it accordingly.

Related Questions

Each of the question below consists of a question and three statements number I, II and III given below it. You have to decide whether the data provided in the statement are sufficient to answer the question. If the bus is travelling from Surat to Ahmadabad and a car is travelling from Ahmadabad to Surat, then what is the distance between Surat and Ahmadabad? I. The speed of a car is 40% less than the speed of bus. Bus started at 9 am and car started at 10 am and they meet at 3 pm of the same day. II. After travelling for 1 hour, because of traffic average speed of bus is decreased by 20% and covers distance between Surat to Ahmadabad in 11 hours. Original speed of car is 20% less than original speed of bus and before crossing bus it covered 200 km if starts 1 hour later than bus. After crossing car, bus covers remaining distance in 5 hours. III. Speed of bus is 10 km/hr more than the speed of car and before crossing car ratio of distances covered bus and car in same time was 5 : 4. Time taken by car to cover the distance between Ahmadabad and Surat is 2 hours 15 minutes more than time taken by bus to cover the same distance.