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# Maths Questions for DSSSB & KVS/NVS Exams

Q1. A, B and C are three taps connected to a tank. A and B together can fill the tank in 6 hr, B and C together can fill it in 10 hr and A and C together can fill it in 7 1/2hr. In how much time all three would take to fill the tank?
(a) 10 hr
(b) 12 hr
(c) 20 hr
(d) 5 hr

Q2. A water tank has two pipes. The empty tank is filled in 12 min by the 1st and the full tank is empty by the 2nd in 20 min. The time required to fill the 1/2 full tank when both pipes are in action, is
(a) 16 min
(b) 15 min
(c) 20 min
(d) 30 min

Q3. A tap can fill a cistern in 40 min and a second tap can empty the filled cistern in 60 min. By mistake without closing the second tap, the first tap was opened. In how many minutes will the empty cistern be filled?
(a) 72 min
(b) 84 min
(c) 108 min
(d) 120 min

Q4. A tap can fill a cistern in 8 hr and another tap can empty it in 16 hr. If both the taps are open, the time (in hours) taken to fill the tank will be
(a) 8 hr
(b) 10 hr
(c) 16 hr
(d) 24 hr

Q5. A pipe can fill a tank with water in 3hr. Due to leakage in bottom, it takes 3 1/2hr to fill it. In what time the leak will empty the fully tank?
(a) 12 hr
(b) 21 hr
(c) 6 1/2 hr
(d) 10 1/2 hr

Q6. A cistern can be filled with water by a pipe in 5 hr and it can be emptied by a second pipe in 4 hr. If both the pipes are opened when the cistern is full, the time in which it will be emptied is
(a) 9 hr
(b) 18 hr
(c) 20 hr
(d) 20 1/2hr

Q7. A tank can be filled by two pipes in 20 min and 30 min, respectively. When the tank was empty, the two pipes were opened. After some time, the first pipe was stopped and the tank was filled in 18 min. After how much time of the start was the first pipe stopped?
(a) 5 min
(b) 8 min
(c) 10 min
(d) 12 min

Q8. Three pipes A, B and C can fill a cistern in 6 hr. After working at it together for 2hr, C is closed and A and B fill it in 7 hr more. The time taken by C alone to fill the cistern is
(a) 14 hr
(b) 15 hr
(c) 16 hr
(d) 17 hr

Q9. A tank can be filled with water by two pipes A and B was together in 36 min. If the pipe B stopped after 30 min, the tank is filled in 40 min. The pipe B can alone fill the tank in
(a) 45 min
(b) 60 min
(c) 75 min
(d) 90 min

Q10. 12 pumps working 6 h a day can empty a completely filled reservoir in 15 days. How many such pumps working 9 h a day will empty the same reservoir in 12 days?
(a) 15
(b) 9
(c) 10
(d) 2
Solutions

S8. Ans.(a)

Sol.
A+B+C = 6 hr
1 × 2 = 2
Remaining = 6 – 2 = 4
A+B = 4/7
C= 1 -(4/7)
C=3/7
Total = (6×7)/3
= 14hr

S9. Ans.(d)
Sol.
A+B = 36 min
30 × 1 = 30
Remaining = 36 – 30 = 6
A = 6/10
A =3/5
B=1-(3/5)
=2/5
B=36/(2/5)
B = 90 min

S10. Ans.(c)
Sol. 12 × 6 × 15 = x × 9 × 12
90 × 12 = x × 9 × 12
x = 10 days