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Pipes and Cistern ( 16 to 20 ):
APTITUDE QUESTIONS (PIPES AND CISTERN):
16. Bucket A has thrice capacity as bucket B. it takes 60 turns for bucket A to fill the empty drum. How many turns will it take for both the buckets A and B, having each turn together to fill the empty drum?
A) 50
B) 40
C) 45
D) 90
E) None of these
View Answer
Answer: option (C)
Explanation:
Let capacity of A be x litres. Then, capacity of B = x/3 litres
Capacity of the drum = 60x litres
Required number of turns = ( 60x / x+(x/3)) = (60x * 3/4x) = 45
17. Two pipes P and Q can fill a tank in 12 minutes and 15 minutes respectively. How much more time will it take to fill the tank by tap Q if both the taps are opened simultaneously and the tap P is closed after 3 minutes?
A) 9 min 15 sec
B) 9 min 45 sec
C) 8 min 5 sec
D) 8 min 15 sec
E) None of these
View Answer
Answer: option (D)
Explanation:
Part filled in 3 min = 3((1/12)+(1/15)) = ( 3 * (9/60)) = 9/20
Remaining part = (1- (9/20)) = 11/20
Part filled by Q in 1 min = 1/15
1/15 : 11/20 : : 1 : x or x = ((11/20)*1*15) = 8(1/4) min = 8 min 15 sec
∴Remaining part is filled by Q in 8 min 15 sec
18. Two pipes X and Y can fill a tank in 15 hours and 20 hours respectively while a third pipe Z can empty the full tank in 25 hours. All the three pipes were opened in the starting. After 10 hours, Z is closed. In how much time, will the tank be full?
A) 12 hrs
B) 13 hrs
C) 16 hrs
D) 18 hrs
E) None of these
View Answer
Answer: option (A)
Explanation:
Part filled in 10 hours = 10((1/15)+(1/20)-(1/25)) = 23/30
Remaining part = (1- (23/30)) =7/30
(X + Y)’s 1 hours work = (1/15)+(1/20)) = 7/60
7/60 : 7/30 : : 1 : x or x = ((7/30)*1*(60/7)) = 2 hours
therefore the tank will be full in (10 + 2) hrs = 12 hours
19. A large tanker can be filled by two pipes X and Y in 60 minutes and 40 minutes respectively. How many minutes will it take to fill the tanker from empty state if Y is used for half the time and X and Y fill it together for the other half?
A) 25 min
B) 20 min
C) 27 min
D) 30 min
E) None of these
View Answer
Answer: option (D)
Explanation:
Part filled by (X + Y) in 1 minute = ((1/60)+(1/40)) = 1/24
Suppose the tank is filled in x minutes
Then, x/2((1/24)+(1/40)) = 1 <=> x/2 * 1/15 = 1 <=> x = 30 min
20. Two pipes X and Y can fill a cistern in 12 minutes and 15 minutes respectively while a third pipe Z can empty the full tank in 6 minutes. X and Y are kept open for 5 minutes in the beginning and then Z is also opened. In what time is the cistern emptied?
A) 30 min
B) 33 min
C) 37 min
D) 45 min
E) None of these
View Answer
Answer: option (D)
Explanation:
Part filled in 5 min. = 5((1/12)+1/15)) = (5*(9/60)) = 3/4
Part emptied in 1min when all the pipes are opened = 1/6 – ((1/12)+(1/15)) = ((1/6)-3/20)) = 1/60
Now, 1/60 part is emptied in 1 min
∴ 3/4 part will be emptied in ((60*(3/4)) = 45 min.