Bissoy.com
Doctors Medicines MCQs Q&A

Pipe P can fill a tank in 5 minutes alone and pipe Q can fill it in 4 minutes. Pipe R alone can empty the same tank in 2 minutes. Pipe P and Q are opened together to fill the tank. After 2 minutes, pipe R is also opened. How much time pipe R will take to empty this tank?  

Pipe P can fill a tank in 5 minutes alone and pipe Q can fill it in 4 minutes. Pipe R alone can empty the same tank in 2 minutes. Pipe P and Q are opened together to fill the tank. After 2 minutes, pipe R is also opened. How much time pipe R will take to empty this tank?   Correct Answer 18 minutes

Given:

P can fill a tank = 5 minutes

Q can fill a tank = 4 minutes

R can empty a tank = 2 minutes

Calculation:

Pipe

Time

LCM (5,4 and 2)

Efficiency(No. of units worked in a day)

 

P

5

 

20 ÷ 5 = 4

Q

4

20

 

20 ÷ 4 = 5

R

(2)

 

20  ÷ 2 = (10)

P+ Q+ (-R)

 

 

4 + 5 -10 = (1)

Work done by all  three   pipes in a minute

 

⇒ Work done by (P + Q) in first 2 minutes = (4 + 5) × 2 = 18 units

⇒ Work done by (P + Q – R) = 18/(1)

∴ R will take 18 minutes to empty the tank.

The correct option is 3 i.e. 18 minutes.

Related Questions

In the following question, two statements are numbered as A and B. On solving these statements, we get quantities A and B respectively. Solve both quantities and choose the correct option. Quantity A: Pipe A takes thrice the time taken by Pipe B to fill a tank. Together they can fill the tank in 15 hours, tank A and B is opened together for 4 hours and then Pipe A is closed and after 2 more hours Pipe B is closed and an outlet Pipe C is opened which when working alone can empty the tank in 10 hours. Calculate the time taken by C to empty the tank. Quantity B: A pipe A can fill the tank in 10 hours another pipe B can fill the tank in 15 hours and with the help of third pipe C they can fill the tank in 5 hours. Pipe A is opened for 4 hours then it is closed, pipe B is closed 3 hours before filling of tank and tank C is opened the whole time. Calculate the time taken to fill the tank
In the following question, two statements are numbered as A and B. On solving these statements, we get quantities A and B respectively. Solve both quantities and choose the correct option. Quantity A: Pipe A takes thrice the time taken by Pipe B to fill a tank. Together they can fill the tank in 15 hours, tank A and B is opened together for 4 hours and then Pipe A is closed and after 2 more hours Pipe B is closed and an outlet Pipe C is opened which when working alone can empty the tank in 10 hours. Calculate the time taken by C to empty the tank. Quantity B: A pipe A can fill the tank in 10 hours another pipe B can fill the tank in 15 hours and with the help of third pipe C they can fill the tank in 5 hours. Pipe A is opened for 4 hours then it is closed, pipe B is closed 3 hours before filling of tank and tank C is opened the whole time. Calculate the time taken to fill the tank.
Given below are three quantities named A, B and C. Based on the given information; you have to determine the relationship between the two quantities. You should use the given data and your knowledge of Mathematics to choose between the possible answers. The options represent the relations between these three quantities A) > B) < C) = D) ≤ E) ≥ Two pipes P and Q can fill an empty tank in 20 minutes and 30 minutes respectively. Quantity A: If both pipes are opened simultaneously, then after what certain time P should be closed so that further time after which the tank is filled in 15 minutes? Quantity B: If both are opened and P is closed after 8 minutes, how much further time would it take for Q to fill the bucket? Quantity C: Pipe A and B can fill a tank in 15 minutes and 10 minutes respectively. Pipe C can empty the tank in 5 minutes. Pipe A and B are opened simultaneously and after the 4-minute pipe, C is also opened. In what time the tank will be emptied?
Pipe P alone can fill a tank in 5 minutes and pipe Q alone can fill it in 4 minutes. Pipe R alone can empty the same tank in 2 minutes. Pipe P and Q are opened together to fill the tank. After 2 minutes, pipe R is also opened. How much time pipe R will take to empty this tank?  
Three pipes x, y and z can fill a tank A can fill it in 4 minutes. Two pipes p and q are connected to tank B. how much time does it take for both tanks to run at the full capacity? Ratio of time taken to fill tank A by P and time taken by x to fill tank A is 2: 1 and ratio of time taken by Q to fill tank B and Z to fill tank A is 5: 3. Pipe P is 20% more efficient then pipe Q. and pipe Y takes 12 minutes to fill the tank. Capacity of tank B is 3/4 times of tank A. Note: Tank B is to be filled only after filling tank A. Valves of pipe p and q are closed once tank B is running at full capacity.
Two pipes are connected to tank 1 and one pipe connects tank 1 and tank 2 at the bottom of both tanks. At first pipe A and pipe B will filling tank 1 and then pipe C would be opened to fill tank 2. Capacity of tank 1 is twice capacity of tank 2. Pipe C takes 8 minutes to fill the whole tank 2 wherein discharging capacity of pipe C is 62.5 liters per minute. Ratio of time taken by pipe A and B to fill the tank when operating alone is 4 : 5 then find approximate discharging capacity of pipe A and B in liters/ minute if both the pipes discharge equal amount of water in tank. Time taken by pipe A and B to fill the tank 1 is 20/ 3 minutes
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. A water tank is to be filled. Pipe A is opened for 10 minutes and then closed. After that pipe, B is opened and the remaining tank is filled by Pipe B alone. In how much time pipe B filled the remaining tank working alone? I. Pipe A and B together can fill a tank in 12 minutes. II. Pipe B, C, can fill a tank in 10 minutes. The ratio of their efficiency is 1 : 2 III. Pipe D and C can fill a tank in 12 minutes
A question is given followed by information in three statements. You have to find out the data in which statement(s) is sufficient to answer the question and mark your answer accordingly. Pipe A can fill the tank in 30 minutes and pipe B also fills the tank in some time. Pipe C alone completely empty the filled tank in 15 minutes, then B alone can fill a completely empty tank when pipe C is shut? I) A, B and C together they fill the tank in 60 minutes. II) A and B together fill the tank in 12 minutes.
Time taken by pipe A and pipe B to fill up the cistern is 12 minutes whereas time taken by pipe C to empty the whole cistern is twice that of time taken by A and B together to fill the tank and ratio of time taken by pipe A and B to fill up the tank when operating alone is 2 : 3. If pipe A and B are alternatively opened every 6 minutes and C is opened with pipe B but closed when pipe A is opened then calculate total time taken to fill up the whole cistern. 
Pipe A is 40% more efficient then pipe E, Pipe B requires 4 minutes less to fill up the tank alone then pipe E, ratio of time taken by Pipe C and pipe A is 5 : 6, pipe C requires 15 minutes to empty the whole tank, if all the pipes are opened together then it requires 48/ 11 minutes to fill up the whole tank. Find the ratio of time taken by pipe B and pipe C to fill up the tank alone.