Bissoy.com
Doctors Medicines MCQs Q&A

Two cities A and B are 600 km apart and from A to B is a downstream journey on a stream which flows at a speed of 10 km/hr. Two boats P and Q run to and fro between two cities. Speed of Boat P, which starts from city A is 50 km/hr while speed of boat Q, which starts from city B at the same time is 30 km/hr. After how much time will two boats meet for the second time?

Two cities A and B are 600 km apart and from A to B is a downstream journey on a stream which flows at a speed of 10 km/hr. Two boats P and Q run to and fro between two cities. Speed of Boat P, which starts from city A is 50 km/hr while speed of boat Q, which starts from city B at the same time is 30 km/hr. After how much time will two boats meet for the second time? Correct Answer 20 hours

Distance between city A and B = 600 km

Speed of boat P = 50 km/hr

Speed of boat Q = 30 km/hr

Speed of the stream = 10 km/hr

As, A to B is the downstream journey,

When boat P travels downstream, effective speed of boat P = 50 + 10 = 60 km/h

Similarly,

When boat Q travels upstream, effective speed of boat Q = 30 – 10 = 20 km/h

Relative speed (as boats are travelling in opposite direction) = 60 + 20 = 80 km/h

Time in which boats will meet for the first time = 600/80 = 7.5 hours

Now,

Time taken by boat P to reach city B = (600/60) = 10 hours

When boat P reaches city B,

Distance travelled by boat Q = 20 × 10 = 200 km

So, boat Q will be at 200 km from city B

As, boat P has reached city B so it will return to city A. Now, direction of boat P will change and hence after 10 hours, both P and Q will be travelling upstream.

When boat P travels upstream, effective speed of boat P = 50 – 10 = 40 km/hr

Relative speed (as boats are travelling in same direction) = 40 – 20 = 20 km/hr

As, Q is ahead of P by 200 km,

Time taken by P to catch Q = (200/20) = 10 hours

∴ P and Q will meet after (10 + 10) = 20 hours for the second time.

Related Questions

What is the distance covered by boat N upstream in 5 hours? Which of the following option is sufficient alone to find the answer? A) Boat M is travelling downstream with 20% more downstream speed of boat N. Speed of boat M in still water is 10% more than the speed of boat N in still water. B) Boat M and Boat N are travelling downstream with speed 33 km/hr and 40 km/hr respectively and speed of boat M is still water is 2 times the speed of stream. C) Speed of boat M in still water is 6 km/hr less then speed of boat N in still water and speed of stream is 10 km/hr. D) Speed of stream is ½ times the speed of boat N in still water and downstream speed of boat M is 44 km/hr. E) Speed of stream is 10 km/hr and ratio of upstream speed of boat M and boat N is 3 : 2 respectively.
Two cities X and Y are 700 km apart. X to Y is a downstream journey on a stream which flows at a speed of 5 km/hr. Two boats A and B run to and fro between two cities. Speed of Boat A, which starts from city X is 45 km/hr, while speed of boat B, which starts from city Y at the same time is 25 km/hr. After how much time will two boats meet for the second time?
Two places are X km apart. Two boats start from each place at the same time towards each other. One is going upstream and another downstream. The speeds of two boats are 12 km/hr and 15 km/hr. Both the boats meet after 4 hours. From the given statement which of the following can be determined? A. Speed of the current. B. Value of X. C. If both the boats travel upstream (Faster boat is behind the slower one) then after how much time will they meet? D. If both the boats travel downstream (Faster boat is behind the slower one) then after how much time will they meet?
Questions below followed by two quantities. Find the relation between them. The table shows the distance travelled by five different boats upstream, the speed of the boat in still water and the time taken by them to cover the upstream distance. Boats Upstream distance Speed of boat Time taken  A  240 km  15 km/hr  20 hr  B  150 km  10 km/hr  25 hr  C  350 km  20 km/hr  50 hr  D  96 km  8 km/hr  16 hr  E  126 km  26 km/hr  9 hr   Quantity I: Boat B travel 238 km distance downstream in certain time. How much downstream distance boat D will cover at the same time? Quantity II: Boat E travel 722 km distance downstream in certain time. How much downstream distance boat A will cover at the same time?
In the following question, two statements are numbered as A and B. On solving these statements we get quantities A and B respectively. Solve for the both quantities and chose the correct option. Quantity A: The ratio of speed of boat to speed of stream is 2 : 1, If the boat travels 162 km and come back to starting point in 36 hour. What is the difference between the time taken by the boat to go upstream and the time taken by the boat to go downstream? Quantity B: The speed of the stream is 6 km/hr and the distance travelled by the boat is 60 km. If the boat covered half distance upstream with usual speed and other half with double its speed, then it takes 7.5 hours less time than usual time to go upstream. Find the total time taken by the boat to go upstream and downstream?
Ratio between speed of boat P and Q in still water is 8∶6 and speed of current is 8 km/hr. Boat Q starts from A in the downstream,2 hours earlier than Boat P and it is found that Boat P is 32 km ahead of boat Q after 16 hours of its start. If boat P starts from point B in down steam at the same time and distance between A and B is 216 km, then find at what time boat P and Q meet each other.
Study the following questions carefully and answer accordingly. Quantity - I) If the time taken by a boat to cover the same distance in upstream is 2 hours more than downstream. The downstream speed of the boat and the speed of current is 16 kmph and 4 kmph then find the total distance travelled by the boat? Quantity - II) If the time taken by the boat in upstream and in downstream is 16 hours and 10 hours to cover the same distance. Then find the speed of boat in still water is how much percent of the speed of stream? Quantity – III) If the length of rectangle is twice of its breadth and 3 times more than the side of square and the difference between the side of square and length of rectangle is 15 cm then find the area of rectangle ?
The question below is followed by three statements I, II, and III. You have to determine whether the data given is sufficient for answering the question. You should use the data and your knowledge of mathematics to choose the best possible answer. The river flows towards the city P from city Q. The distance between City P and City Q is 360 km. Two boats A and B run daily from city P and Q respectively at the same time and come back. Find the time when they meet the second time. Statement I: Boat A can cover 120 kilometers distance in 360 minutes in still water. Statement II: Boat B can travel 120 kilometers distance in 450 minutes in still water. Statement III: Boat B can cover 360 kilometers against the flow of the river in 1800 minutes.
Two boats go downstream in a river at a speed of 15 km/hr and 20 km/hr. The speed of the stream is 4 km/hr. The distance between both the boats is 30 km. In how much time will they meet if the boats are going downstream?
Boat A started from Goa to Kolkata at the same time, Boat B started from Kolkata to goa both the boats travelled at constant speed. The Boats meet each other for the first time in 24 hours after starting. Two boats reached their respective sources i.e A to goa and B to Kolkata in 8 hrs and 50 hr respectively after they crossed each other. If the difference of the distance covered by them is 75 km. After how many kms from the starting points (By boat A) they crossed each other.