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The distance between two stations A and B is 440 km. A train starts at 4 p.m. from A and move towards B at an average speed of 40 km/hr. Another train starts B at 5 p.m. and moves towards A at an average speed of 60 km/hr. How far from A will the two trains meet and at what time?

Option: 1

200,8 p.m.


Option: 2

300,9 p.m.


Option: 3

200,9 p.m.


Option: 4

300,8 p.m.


The sum of the distances covered by both trains should be equal to the total distance between the stations A and B: 40t+60(t−1)=44040t + 60(t - 1) = 44040t+60(t−1)=440

40t+60t−60=440
100t−60=440
100t=500
t=5

So, the trains will meet 5 hours after Train A starts from A.

Train A starts at 4 p.m. so 5 hours from 4 p.m. is 4 p.m. + 5 hours = 9 p.m.

The two trains will meet 200 km from A at 9 p.m.

Option 3: 200, 9 p.m.

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Posted by

Sara P

PQ is a tunnel. A dog sits at the distance of 5/ 11 of PQ from P. The train whistle coming from any end of the tunnel would make the dog run. If a train approaches P and dog runs towards P the train would hit the dog at P. If the dog runs towards Q instead, it would hit the dog at Q. Find ratio of speed of train and dog?

 

Option: 1

5:2


Option: 2

16:5


Option: 3

11:1


Option: 4

34:3


Option 3 - 11:1

########            P____5_____¶______6_____Q

"¶" is the dog located inside the tunnel PQ and #####... is a train approaching to it. 

Case 1 - Dog decides to reach point P 

Distance covered by Dog - 5 parts and train reaches at P

Case 2 - Dog decides to run towards point Q

At the time train reaches to point P, the dog covers 5 parts in direction of Q. Now the left out part covered by dog will be 1 part towards Q .

At the time dog covers 1 part and reaches Q, train covers whole 11 parts of tunnel and reaches from P to Q. 

So, 11 part of train is eual to the 1 part covered by the dog to reach Q. 

Ratio of their speeds - Train:Dog = 11:1  

 

 

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Posted by

Vaibhavi Gupta

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A boat covers a certain distance downstream in 4 hours but takes 6 hours to return upstream to the

A boat covers a certain distance downstream in 4 hours but takes 6 hours to return upstream to the starting point. If the speed of the stream be 3 km/hr, find the speed of the boat in still water

  • Option 1)

    15 km/hr

  • Option 2)

    11 km/hr

  • Option 3)

    13 km/hr

  • Option 4)

    14 km/hr

  • Option 5)

    12 km/hr

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Posted by

rishi.raj

A man can row 40 kmph in still water and the river is running at 10 kmph. If the man takes 1 hr to

Option 5

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Posted by

Affan

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At his usual rowing rate, Rahul can travel 12 miles downstream in a certain river in 6 hours less t

At his usual rowing rate, Rahul can travel 12 miles downstream in a certain river in 6 hours less than it takes him to travel the same distance upstream. But if he could double his usual rowing rate for his 24-mile round trip, the downstream 12 miles would then take only one hour less than the upstream 12 miles. What is the speed of the current in miles per hour?

  • Option 1)

    213 mph

  • Option 2)

    113 mph

  • Option 3)

    217 mph

  • Option 4)

    223 mph

  • Option 5)

    123 mph

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Posted by

rishi.raj

The speed of a boat in stll water is 10 km/hr. If its speed downstream be 13 km/hr, then speed of the stream is:

Speed of a boat in still water=10km/hr

Speed of down stream=13km/hr

Speed of stream is=u-v=13-10=3km/hr

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Posted by

HARIVENDRAREDDY

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A boat goes 14 km upstream in 56 minutes. The speed of stream is 2 km/hr. The speed of boat in still water is

14×60/56=15km/hr

Upstream=X-Y

15=X-2

X=15-2

X=17

 

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Posted by

Rohit Shirole

Two men A and B started walking towards each other’s starting point simultaneously from two p

3

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Posted by

Reshmi kumari

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A police man was travelling @ 90kmph. He crosses a thief travelling @ 60kmph in opposite direction.

A police man was travelling @ 90kmph. He crosses a thief travelling @ 60kmph in opposite direction. He had to travel for another 6 minutes before he would U turn and chase the thief? After they crossed each other how long in minutes police will catch the thief?

  • Option 1)

    30

  • Option 2)

    36

  • Option 3)

    35

  • Option 4)

    45

  • Option 5)

    42

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Posted by

rishi.raj

PQ is a tunnel. A dog sits at the distance of 5/ 11 of PQ from P. The train whistle coming from any

PQ is a tunnel. A dog sits at the distance of 5/ 11 of PQ from P. The train whistle coming from any end of the tunnel would make the dog run. If a train approaches P and dog runs towards P the train would hit the dog at P. If the dog runs towards Q instead, it would hit the dog at Q. Find ratio of speed of train and dog?

  • Option 1)

    5:2

  • Option 2)

    16:5

  • Option 3)

    11:1

  • Option 4)

    4:5

  • Option 5)

    34:3

View Full Answer(1)
Posted by

rishi.raj

JEE Main high-scoring chapters and topics

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