Two stations A and B are 110 km apart on a straight line. One train GMAT Problem Solving

Question: Two stations A and B are 110 km apart on a straight line. One train starts from A at 7:00 AM and travel towards B at 20 kmph. Another train starts from B at 8:00 AM and travel towards A at 25 kmph. At what time they will meet?

  1. 09:00 AM
  2. 09:30 AM
  3. 10:00 AM
  4. 10:30 AM
  5. 11:00 AM

Correct Answer: C

Solution and Explanation
Approach Solution 1:

It is given that Two stations A and B are 110 km apart on a straight line. One train starts from A at 7:00 AM and travel towards B at 20 kmph. Another train starts from B at 8:00 AM and travel towards A at 25 kmph.

And it is asked At what time they will meet?
Train leaving from A will travel 20 kilometres between 7 AM and 8 AM.
110 minus 20 equals 90 kilometres, the remaining distance.
Trains' relative speed is 20 + 25 = 45 kmph.
Time needed to meet after 8 AM is 90/45 minutes, or 2 hours.
They will gather at 10 a.m. (8 plus 2).

Approach Solution 2:
There is another approach to solve this question which is based on assumption

Let us suppose they meet x hours after 7 a.m.
So, Distance covered by A in x hours will be 20 x km.
Same way ,
Distance covered by B in (x - 1) hours will be 25(x - 1) km
Therefore,
20x + 25[x - 1] = 110
= 45x = 135
x = 3
They will meet at 7+3 = 10 am

Approach Solution 3:
Distance between A and B is 110 km
Speed of first train is 20 km/hr
Speed of secod train is 25 km/hr

Relative speed both train if they running opposite direction is= (20-25)= 45 km/h

Distance covered by first trainin 1 hr is 20 km

Remaining distance= (110-20)= 90 km

Time= distance/speed
Time= 90/45= 2 hrs

Therefore, the required time is 8 am + 2 hrs= 10 hrs. 

“Two stations A and B are 110 km apart on a straight line. One train”- is a topic of the GMAT Quantitative reasoning section of GMAT. To solve GMAT Problem Solving questions a student must have knowledge about a good amount of qualitative skills. GMAT Quant practice papers improve the mathematical knowledge of the candidates as it represents multiple sorts of quantitative problems.

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