## Pipes & Cisterns Solved Questions For IBPS, SBI and Other Bank Exams - Page 5

Pipes & Cisterns Solved Questions (Page 5 of 5)

**Question 1**

Two pipes X and Y together can fill a tank in 72 minutes. If the size of the pipe X is thrice as Y then Y alone can fill the tank in:

a) 5 hours and 12 minutes

b) 3 hours and 56 minutes

c) 4 hours and 48 minutes

d) none of these

**Answer : **c) 4 hours and 48 minutes.

Solution :

Let the time taken by Y alone to fill the tank be A minutes.

Given that, the size of the pipe X is thrice as Y.

Then, X fills the tank in A/3 minutes.

Part filled by X in 1 minute = 1/(A/3) = 3/A

Part filled by Y in 1 minute = 1/A.

Since, X and Y together take 72 minutes.

Part filled by (X+Y) in 1 minute = 1/72

i.e., (1/A + 3/A) = 1/72

4/A = 1/72

A = 288 minutes = 288/60 hours = 4 + 48/60 = 4 + 4/5 hours

= 4 hours and 4/5 x 60 minutes = 4 hours and 48 minutes.

Hence, the pipe Y alone takes 4 hours and 48 minutes to fill the tank.

**Question 2**

Pipe X can fill a cistern thrice as fast as another pipe Y and the pipe Y is thrice as fast as pipe Z. If X, Y and Z together fill the cistern in 10 minutes then the time taken by X to fill the cistern is:

a) 1 hour and 42 minutes

b) 2 hours and 10 minutes

c) 1 hour and 23 minutes

d) none of these

**Answer : **b) 2 hours and 10 minutes

Solution :

Let the pipe Z alone takes A minutes to fill the tank.

Given that, Y is thrice as fast as Z.

Then, Y takes A/3 minutes to fill the tank.

And, X is thrice as fast as Y.

X takes (A/3)/3 = A/9 minutes to fill the tank.

Now,

Part filled by X in 1 minute = 9/A

Part filled by Y in 1 minute = 3/A

Part filled by Z in 1 minute = 1/A

Net part filled by (X+Y+Z) in 1 minute = 9/A + 3/A + 1/A = 13/A

(X+Y+Z) take 10 minutes to fill the cistern.

Part filled by (X+Y+Z) in 1 minute = 1/10

Thus, we have, 1/10 = 13/A

A = 130

Therefore, Z alone takes 130 minutes i.e., 2 hours and 10 minutes.

**Question 3**

Pipe X takes 6 hours to fill a cistern and another pipe Y takes 7 and half hours to fill the same cistern. If the pipes X and Y are switched together at the same time and X is closed after 1 and half hours then the extra time taken by Y to fill the cistern is:

a) 39/8 hours b) 41/8 hours c) 37/8 hours d) none of these.

**Answer : **a) 39/8 hours

Solution :

X takes 6 hours, part filled by X in 1 hour = 1/6

Y takes 7 and half hours, part filled by Y in 1 hour = 1/7.5 or 2/15.

Therefore, the part filled by X and Y together = 1/6 + 2/15

X and Y together fill the cistern for 1 and half hour i.e., 3/2 hours.

Part filled by (X+Y) in 3/2 hours = (3/2)(1/6 + 1/15) = (3/2)(7/30) = 7/20

Remaining part filled by Y alone = 1 - 7/20 = 13/20.

Part Filled Time Taken by Y 2/15 1 hour 13/20 ?

Time taken to fill 13/20 part by Y alone = 13/20 x 15/2 = 39/8 hours.

Pipes & Cisterns Solved Questions (Page 5 of 5)