# Pipes & Cistern Quiz For Upcoming Exams Solution

1. (b) (Total capacity)
60
Efficiency 3 2
Hour → 20 30
(A) (B)
filling pipe
According to questions,
Pipe ‘A’ is closed after some time.
And Tank is filled in 18 minutes so
B started filling in beginning and
Worked till last i.e. 18 minutes
So, 2×18 = 36 units is filled
Work left = 60 – 36 = 24 units
This 24 units must be filled by Pipe
A in beginning.
It can fill it in
= 8 minutes

2. (d)
Efficiency
Hours →
(filling) (emptying)
Total efficiency of both pipes is
Tank will be filled in

3. (c) Apply formula of
Let ‘P’ pumps are required to empty the
Reservoir.
P = 10 pumps

4. (a) Pipe A : Pipe A-leakage
Efficiency → 2 : 1
Time 1 : 2
×36 1 unit = 36 hrs
36 hrs

5. (d) let (A+B) fills 1 liter in 1 minutes
Then (A+B) fills in 36 minutes = 36 liters
According to question
(A+B) work only 30 minutes then pipe filled by
(A+B) in 30 minutes is = 30 liters
Remaining part = 6 liters
6 liters part filled by A in = 10 minutes
1 part filled by A =
minutes
36 part filled by A =
= 60 minutes
A + B = 36 minutes
A = 60 minutes
(T.W)
180
Efficiency 3 5 liters/minute
60 36
(A) (A+B)
A’s efficiency = 3 liters/minutes
B’s efficiency = 2 liters/minutes.
B can alone fill the tank in
=
= 90 minutes

6. (c) (Total capacity)
120
Efficiency → 6 5 8
Hours → 20 24 15
(A) (B) (A+B+C)
(A+B+C) one day work = 8
6+5–C = 8
11–C = 8
C = 3
C = 3 units T.C = 120
×1 ×1
Actual 3 Galons 120 units
emptying
capacity
= 120 galons

7. (d)
120
Efficiency → 30 15 10 –12
Hours → 4 8 12 10
(P) (Q) (R) (S)
In order to fill the cistern in less time.
So, efficiency of filling should be more
Now, check all options
(A) → Q efficiency 15 units/hr
(B) → (P + R – S) efficiency
= 30+10–12 = 28 units/hr
(C) → (P + S) efficiency = 30 – 12
= 18 units/hr
(D) → (P + Q – S) efficiency
= 30+15–12 = 33 units/hr
Since efficiency of option ‘D’ is highest.

8. (d) (Total capacity)
30
Efficiency→ 3 2
Hours → 10 15
(–A) (–A+B)
Emptying Filling
Pipe A is emptying at 3 units/hr
When filling pipe ‘B’ start function
then emptying rate comes down to
2 units/hr
So, filling pipe efficiency is
(3–2) = 1 unit/hr
Pipe ‘B’ will fill tank in =
= 30 hrs
Filling rate is 4 liters/minutes
It will fill 4×60 = 240 liters/hr.
Total capacity = 240×30 = 7200 liters

9. (c) (Total capacity)
12
Efficiency→ 3 2
Hours → 4 6
(A) (B)
A will fill 3 units of water in Ist hour
B will fill 2 units of water in IInd hours
5 units in 2 hours
5 units is filled in 2 hours
×2 ×2
10 units 4 hours
Work left = 12–10 = 2 units
Now, A will begin he completes 2
Units in
hours
Total time = 4
hours

10. (c) Qty Time(in minutes)
Boy → 4 liters 3
Girl→ 3 liters 4
Boy → (4 3)×4 = 16 liters
In 12 minutes
Girl→ (3 4)×3 = 9 liters
In 12 minutes
(Boy + Girl) pour
25 liters 12 minutes
×4 ×4
100 liters 48 minutes