Question: The metro service has a train going from A to B and from B to A every hour, the first one at 6 AM. The trip from one city to other takes 4.5 hours, and all trains travel at the same speed. How many trains will you pass while going from A to B if you start at 12 noon?

1. 8
2. 9
3. 10
4. 13
5. 12

Correct Answer: B
Solution and Explanation:

Approach Solution 1:

This is a GMAT problem-solving question in which you have to use the details given in the question to solve the problem. The problem in this category are coming from different areas of math topics. This one particularly is from time and distance.

The option is given in such a way that it is difficult to guess the correct answer. The candidates need to know the right approach to get the required answer. Only one of the given five choices is correct.

At midday, the train departs from A for B. I'll call it X.
At 4:30 PM, train X arrives at destination B.

X will encounter every train departing from B along the way, and it will arrive at station A between 12:00 and 4:30 PM.
The following trains are among the ones with arrival times between A >= 12 and A < 4:30 PM.
trains departing at 8 a.m., 9 a.m., 10 a.m., and 11 a.m. = 4 trains

Along the way, X will also encounter all trains that depart from Station B between the hours of 12 and 4:30 PM.
The following trains are among those with start times between B > 12 and 4:30 PM.
Trains departing at 12 noon, 1 pm, 2 pm, 3 pm, and 4 pm total five trains.
Nine trains in total.

B is the correct answer.

Approach Solution 2:

This is a GMAT problem-solving question in which you have to use the details given in the question to solve the problem. The problem in this category are coming from different areas of math topics. This one particularly is from time and distance.

The option is given in such a way that it is difficult to guess the correct answer. The candidates need to know the right approach to get the required answer. Only one of the given five choices is correct.

At 12 o'clock, we begin moving from point A toward point B. As a result, the 11 o'clock train from point A to point B will always be one hour earlier than the 1 o'clock train (since all trains have the same speed). Therefore, we don't need to worry about missing any trains that are headed from A to B.

Anytime between 12 and 4:30, we will meet any train that is on the track from B to A.

We won't be able to meet the train that departs from B at 7:00 am and arrives at A at 11:30 am. We will meet the 8:00 am train from B to A, as well as each following train until the one that departs at 4:00 pm.
So, 9 trains from B to A will meet us there.

Answer (B)

Approach Solution 3:

Last train (From B to A) that will Pass us = Train of 4 PM; As our train will reach to B at 4.30 PM
Therefore, total no. of trains (From B to A), that we will pass, will run every hour starting from 8 AM to 4.00 PM i.e. 8 AM, 9 AM, 10 AM, 11 AM, 12 PM, 1 PM, 2 PM, 3 PM and 4 PM
Total = 9

“The metro service has a train going from A to B and from B to A every" - is a topic of the GMAT Quantitative reasoning section of GMAT. This question has been borrowed from the book “GMAT Official Guide Quantitative Review”.

To understand GMAT Problem Solving questions, applicants must possess fundamental qualitative skills. Quant tests a candidate's aptitude in reasoning and mathematics. The GMAT Quantitative test's problem-solving phase consists of a question and a list of possible responses. By using mathematics to answer the question, the candidate must select the appropriate response. The problem-solving section of the GMAT Quant topic is made up of very complicated math problems that must be solved by using the right math facts.

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