RRB Group-D Model Paper 17 with answers for online practice

Question : 68 of 100

Marks: +1, -0

At 9 am, a train starts from Station A towards Station B at 70 km per hour. After 2 hours, another train starts from Station B towards Station A at 20 km per hour. If the distance between the two stations is 320 km, then at what time do the trains meet?

11 am
1 pm
3 am
2 pm

Validate

Solution:

Given:
Train A starts at 9 am at speed 70 km / hr
Train B starts at 11 am at speed 20 km / hr
Distance between two stations 320 km
Formula Used:
When the two objects travel in the same direction their relative speed = (a – b) km / hr
When the two objects travel in the opposite direction their relative speed = (a + b) km / hr
Where a and b are speeds of two objects in km / hr and (a > b)
Speed = Distance / Time
Calculation:
Distance covered by train A in

1^{st}

two hours = Speed × time
⇒ 70 km / hr × 2 = 140 kms
Remaining Distance = 320 km – 140 km = 180 km
From 11 am train B also start running at speed of 20 km / hr
∴ Relative speed of both the trains = (70 km / hr + 20 km / hr) = 90 km / hr
Time taken = Distance / speed
⇒ 180 / 90 = 2 hrs
∴ Both the trains meet at 1 pm

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