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Two stations A and B are 80 km apart on a straight line. One train starts from Station A at 7 a.m. and travels towards B at 20 kmph. Another train starts from Station B at 8 a.m. and travels towards A at a speed of 40 kmph. At what time will the two trains meet?
1. 9.05 a.m.
2. 9.20 a.m.
3. 8.30 a.m.
4. 9.00 a.m.

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Correct Answer - Option 4 : 9.00 a.m.

Given :

Two stations A and B are 80 km apart 

Train from A starts at 7 a.m with speed of 20 kmph

Train from B starts at 8 a.m with speed of 40 kmph

Concept used :

Relative speed 

If vehicles are moving in opposite direction then speeds are added

if vehicles are moving in same direction then speeds are subtracted

Calculations :

Train A starts at 7 a.m with speed of 20 kmph 

Distance covered by train in 1 hour = 20 × 1 (Distance = speed × time)

⇒ 20 km 

Now at 8 a.m distance between stations = 80 - 20 = 60 km 

Now time taken after 8 a.m when both trains will meet = (Distance/speed)

⇒ 60/(20 + 40) (speeds are added because they are moving in opposite direction)

⇒ 60/60 

⇒ 1 hour

Train will meet 1 hour after 8 a.m 

∴ Both the trains will meet at 9 a.m

 

 

 

 

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