A leaves station P at 8 : 00 a.m. and reaches station Q at 11 : 00 a.m. B leaves station Q at 9 : 00 a.m. and reaches station P at 11 : 00 a.m. At what time will they cross each other?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 9 : 48 am.
Calculations:
Time taken by A to cover the distance = 3 hours
Time taken by B to cover the distance = 2 hours
Speed is inversely proportional to time
So,
Speed of A = 2 km/h
Speed of B = 3 km/h
Let the distance be 6 km (LCM of 3 and 2)
In the time period of 8 am to 9 am, A covers a distance of 2 km
Remaining distance = 6 - 2 = 4 km
Hence both the trains are travelling towards each other, the speed will add.
Relative speed = 2 + 3 = 5 km/h
Required time taken = 4/5 hours = 48 minutes
Hence, the time at which the two trains will cross each other is 9 : 48 am