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Description : A tank can be filled by a tap in 8 hrs while it can be emptied by another tap in 18 hrs. if both the taps are opened simultaneously, then after how much time will the cistern get filled? A) 14hrs 24mins B) 14 hrs 12 mins C) 14hrs 56 mins D) 14hrs 30mins
Last Answer : A Net part filled in 1hr = (1/8 – 1/18) = 9 – 4/72 = 5/72 Therefore the tank will be filled in 72/5 hrs i.e., 14 hrs 24mins
Description : Two taps P and Q can fill a cistern in 24 min and 32 min respectively. Both the taps are opened together for a certain time but due to some obstruction the flow of water was restricted to 7/4 of full flow in tap P and ... How long was it before the full flow. A) 8 min B) 3 min C) 5.6 min D) 4.5 min
Last Answer : D Let the obstruction remain for X min. Hence, Part of cistern filled in X min + part of cistern filled in 6 min = full cistern [(7X/4*24)+(5X/3*32)]+[(6/24)+(6/32)] = 1 (12X/96)+(7/16) = 1 12x/96=9/16 Thus, X = 4.5 min.
Description : Pipe A can fill a water tank in 8 hours, Pipe B can fill the same tank in 12 hours and Pipe C can empty the tank in 24 hours. If all three pipes are opened together, in how many hours will the tank be completely filled or empty? a) 4.8 hours b) 5 hours c) 5.4 hours d) 6 hours e) 7.2 hours
Last Answer : If all the three pipes are opened together, in one hour they will fill 1/8 + 1/12 – 1/24 = (3+2-1)/24 = 1/6 part of tank. So, to fill it completely it will take 6 hours. Answer is: d)
Description : Two pipes A and B can fill a tank in 5 and 6hrs.Pipe C can empty it in 12hrs.If all the 3 pipes are opened together,then the tank will be filled in 1)1(13/17)hrs 2)2(8/11)hours. 3)3(9/17)hrs 4)4(1/2)hrs
Last Answer : 3)3(9/17)hrs Exp:Net part filled in 1hr=>(1/5+1/6-1/12)=17/60 Tank filled in=60/17=3(9/17).
Description : Two taps P and Q can separately fill a tank in 120mins and 150 mins respectively. There is a 3rd tap in the bottom of the tank to empty it. If all of the 3 taps are simultaneously opened, then the tank is full ... . In how much time the 3rd pipe alone can empty the tank? A) 100 B) 200 C) 300 D) 400
Last Answer : B Work done by the 3 tap in 1 min = 1/100 – ( 1/120 + 1/150) = 1/100 – (5+4/600) =1/100 – 9/600 =6-9/600 = - 3/600 = - 1/200(negative signs mean empting) Therefore the 3rd tap alone can empty the tank in 200 mins
Description : A water cistern is two-fifth full. Tap A can fill a cistern in 20 mins and tap B can empty it in 12mins. If both the taps are open, how long will take to empty or fill the cistern completey? A) 10 mins B) 12mins C) 14mins D) 16 mins
Last Answer : B Clearly tap B is faster than the Tap A and so, the cistern will be emptied Part to be emptied = 2/5 Part emptied by (A+B) in 1 min = (1/12 – 1/20) = 5-3/60 = 2/60 =>1/30 Therefore 1/30 : 2/5 :: 1;x x= 1*2/5 *30/1 = 12mins so the tank will be emptied in 12mins.
Description : Pipes P, Q and R which fill the tank together in 12 hours are opened for 2hours after which pipe R was closed. Find the number of hours taken by pipe R to fill the tank if the remaining tank is filled in 14 hours. A) 16 B) 14 C) 20 D) 42
Last Answer : D 1/P + 1/Q + 1/R = 1/12 Now given that first all open for 2hours, then R closed and P+Q completes in 14 hours, so (1/P + 1/Q + 1/R) *2 + (1/P + 1/Q)*14 = 1 Put 1/P + 1/Q = 1/12 – 1/R (1/12 – 1/R + 1/R) *2 + (1/12 – 1/R)*14 = 1 1/6+ 14/12 – 14/R = 1 Solve, R = 42
Description : Two pipes, Xand Y can fill a tank in 36 and 30 minutes respectively. Both are opened together, but at the end of 3minutes, X is turned off. In how many more minutes will Y fill the cistern? A) 7(24/5) B) 7(1/2) C) 24(1/3) D) 8(1/4)
Last Answer : C X can fill cistern in 36 minutes. X fills cistern in 1 minute = 1/36 Y can fill cistern in 30 minutes. Y fills cistern in 1 minute = 1/30 part. Xand Y together can fill cistern in 1 minute, = {(1/ ... part. 147/180 part cistern must be filled by Y in, [(147/180)/(1/30)] = 24(1/3) minutes.
Description : Tap 1 can fill a tank in 10 hrs , tap 2 in 20 hrs and tap 3 in 60 hrs. if all the taps are open, in how many hour will the tank be filled? A) 3 hrs B) 5 hrs C) 7hrs D) 6 hrs
Last Answer : D Net part filled in 1 hr = 1/10 + 1/20 + 1/60 = 6 + 3 + 1/60 = 10/60 = 1/6 Therefore all the 3 taps together fill tank in 6 hrs
Description : A tank is filled by 3 taps K, L and M with uniform flow. The second tap L takes 3 times the time taken by K to fill the tank, while M takes two times the time taken by L to fill the tank. If all ... hours, find the time required by tap K alone to fill the tank. A) 10hrs B) 21hrs C) 14hrs D) 22hrs
Last Answer : B 1/x + 1/ (3x) + (1/6x) = 1/14 9/6x= 1/14 6x/9 = 14 6x=126 X=126/6 X=21
Description : A cistern is filled in 15 hours by three pipes P, Q and R. The pipe R is thrice as fast as Q and Q is thrice as fast as P. How much time will pipe P alone take to fill the tank? A) 120 hrs B) 195 hrs C) 135 hrs D) Cannot be determined
Last Answer : B Suppose pipe P alone takes x hours to fill the tank. Then, pipes Q and R will take x/3 and x/9hours respectively to fill the tank. 1/x + 3/x + 9/x = 1/15 13/x = 1/15 => x = 195 hrs.
Description : One tap can fill a cistern four times as fast as another tap. If together the two taps can fill the cistern in 48 mins then the slower tap alone will be able to fill the cisterns. A) 1hr B) 2hr C) 3hr D) 4hr
Last Answer : D Let the slower tap alone fill the cistern in x mins Then faster tap will fill it in x/4 mins Therefore 1/x +4/x = 1/48 5/x = 1/48 X = 48*5 x = 240 mins x = 4 hrs.
Description : Taps P, Q and R can fill a tank in 3, 4 and 5 hours respectively. If all the taps are opened together and after 30 minutes taps Q and R are turned off, find the total time in which the tank is full. A) 2(3/8)hrs B) 1(1/7)hrs C) 2(13/40)hrs D) 3(13/43)hrs
Last Answer : C In 1 hr P, Q, R = 1/3+1/4+1/5 = 20+15+12/60 = 47/60 Filled in 30m = 47/120 Remaining = 1-47/120 =73/120 Tap P = 3*73/120= 219/120 Total = 219/120+1/2 =219+60 /120= 279/120= 2 13/40 hrs
Description : 24 pumps are connected to a tank. Some of them are inlet pumps and the others are outlet pumps. Each of the inlet pumps an fill the tank in 16hours and each of the outlet pumps can empty the tank completely in ... gets filled in 48 hours. How many inlet pumps are there? A) 16 B) 18 C) 17 D) 14
Last Answer : D (x/16)-[(24-x)/12] = 1/48 x/16-24/48+x/12=1/48 (3+4)x/48=97/48 7x/48=97/48 7x=97 X=14
Description : Two taps A and B are opened together to fill a tank. Both the taps fill the tank in time x If B separately took 25 minutes more time than x to fill the tank and B took 49 minutes more time than x ... the tank, then find out the value of x? A) 48 minutes B) 24 minutes C) 54 minutes D) 35 minutes
Last Answer : D Time is taken to fill the tank by both taps x = √a*b x = √25*49 => 5*7 => 35
Description : Two pumps P & Q can fill a tank in 12 mins and 15 mins respectively while a third pipe R can empty the full tank in 6 mins. P & Q kept open for 5 mins in the beginning and then R is also opened. In what time is tank emptied? A) 30mins B) 35mins C) 40mins D) 45 mins
Last Answer : D Part filled in 5 min = 5(1/12 +1/15) = 5*9/60 = ¾ Part emptied in 1 min when all the pumps are opened, = 1/6 – (1/12 + 1/15) = 1/6 – 3/20 = 1/60 Now 1/60 is part emptied in 1 min Therefore ¾ part will be emptied in 60 * ¾ = 45 mins
Description : Two pipes P and Q can fill a cistern in 15 minutes and 20 minutes respectively. Both are opened together, but at the end of 5 minutes, the pipe P is t
Last Answer : Two pipes P and Q can fill a cistern in 15 minutes and 20 minutes respectively. Both are opened ... will the pipe Q take to fill the cistern ?
Description : Pipe A usually fills a tank in 2 hours. On account of a leak at the bottom of the tank, it takes pipe A 30 more minutes to fill the tank. How long will the leak take to empty a full tank if pipe A is shut? a) 4 hours b) 3 hours c) 6 hours d) 8 hours e) 10 hours
Last Answer : portion of the tank filled by the pipe A in 1 hour = ½ of the tank let the portion of the tank emptied because of the leak in 1 hour be 1/x of the tank therefore, in 1 hour , portion of the tank filled = 1/2 - 1 ... 1/2 - 1/x = 1/2.5 or x = 10 hence, it takes 10 hours to empty a full tank Answer: e)
Description : Faucet A basically used as inlet pipe and Faucet B is used as outlet pipe. Faucet A and B both are opened simultaneously, all the time. When Faucet A fills the tank and Faucet B empty the tank, it will take thrice the ... efficiency of Faucet A and Faucet B respectively? a) 1:2 b) 2:1 c) 1:3 d) 3:1
Last Answer : B Efficiency when both pipes used to fill = A + B And efficiency when Faucet A is used to fill and Faucet B is used to empty the tank = A-B So (A+B)/(A-B)=3/1 A/B+1/(A/B-1)=3/1 A/B+1=3(A/B-1) 3A/B-A/B=4 2A/B=4 A/B=2 Thus, the ratio of efficiency of Faucet A and B =2:1
Description : Two faucet A and B can fill a tank in 20 hours and 40 hours respectively. If they are opened simultaneously. Sometimes later, tap B was closed, then it takes total 14 hours to fill up the whole tank. After how many hours B was closed? A) 4 hours B) 15.2 hours C) 12 hours D) 17.6 hours
Last Answer : A Let x is the time when B is closed X(1/20+1/40)+14/20=1 X=4 hours
Description : One tap can fill a tank thrice as fast as another tap. If together the two taps can fill the tank in 12 minutes, then the slower tap alone will be able to fill the tank in A) 30min B) 33min C) 32min D) 35min
Last Answer : C (1/x)+(1/3x)=(1/12) 3+1/3x = 4/3x = 1/12 3x = 48 x=32mins
Description : You have accidently left out the plug and are attempting to fill the bath with both taps full on. The hot tap takes 6 minutes to fill the bath. The cold tap takes 2 minutes and the water empties through the plug hole in 4 minutes.In how many minutes will the bath be filled? -Riddles
Last Answer : 2 minutes and 24 seconds.
Description : two pipes X and Y can fill a cistern in 18 hrs and 24 hrs respectively. If both the pumps are opened simultaneously. How much time will be taken to fill the cistern? A) 10hrs 50mints B) 10 hrs 5mints C) 10hrs 17mints D) 10hrs 44mints
Last Answer : C Part filled by x in 1hour = 1/18 Part filled by y in 1 hour = 1/24 Part filled by (x+y) in 1 hour = 1/18 + 1/24 =>4+3/72 =>7/72 The cistern will be full in 72/7 hrs = 10 hrs 17mins.
Description : Two tap can fill a dumper in 7 hrs and 8 hrs respectively. The taps are opened simultaneously and it is found that due to leakage in the bottom it took 16 mins more to fill the dumper. When the dumper is full, in what time will the leak empty it? A) 56hrs B) 56hrs C) 46hrs D) 36hrs
Last Answer : A Work done by 2 taps in 1 hr = (1/7 + 1/8) = 15/56 Time taken by these taps to fill the dumper = 56/15 hrs =3 hrs 44 mins Due to leakage, time taken = 3 hrs +44mins+16 mins =4hrs Work done by (2 ... the leak in 1 hr = (15/56 - ¼) =15 - 4/56 =1/56 Leak will empty the full cistern in 56 hrs.
Description : A tube can fill a tank completely in 18 hours. After half the tank is filled , one more similar tube is opened. What is the total time taken to fill the tank completely ? A) 14hrs 20min B) 13hrs 30min C) 13hrs 10min D) 14hrs 30min
Last Answer : C A tube can fill the half tank in 9hrs Now another similar tube opened 1/18+1/18 = 2/18 = 1/9 Remaining half tank filled in 4.5hrs Total time = 9+4.5 =13.5 = 13hrs 30min
Description : Two taps can fill a tank in 4 hours and 5 hours .If two taps are operate simultaneously, In how much time will the tank be filled ? A) 4hrs 18min B) 10min 12min C) 2hrs 13min D) 12hrs 10min
Last Answer : C 1/(A+B) =1/4 + 1/5 = (5+4)/20 = 9/20 =>20/9=2hrs 13min to filled the tank
Description : Three pipes P, Q and R can fill a tank from empty to full in 40 minutes, 15 minutes, and 30 minutes respectively. When the tank is empty, all the three pipes are opened. P, Q and R discharge chemical solutions X, Y and Z respectively. ... 5 minutes? a) 8 / 15 b) 7 / 15 c) 8 / 17 d) 6 / 13 e) 8 / 13
Last Answer : a Part of the tank filled by pipe P in 1 minute = 1 / 40 Part of the tank filled by pipe Q in 1 minute = 1 / 15 Part of the tank filled by pipe R in 1 minute = 1/ 30 Here we have to find the proportion of ... together in 5 minute = 5 1/8 = 5/ 8 Required proportion = (1/3) / ( 5/8) = 8 / 15
Description : A tank can be filled by an inlet tap at the rate of 8 litres per minute. A leak in the bottom of a tank can empty the full tank in 16 hours. When the tank is full, the inlet is opened and due to ... hours. How many litres does the tank hold? A) 8000 litre B) 9560 litre C) 8525 litre D) 9600 litre
Last Answer : D Part emptied by the leak in 1 hour = 1/16 part filled by (leak & inlet open) in 1 hour = 1/80 Part filled by the inlet tap in 1 hour = 1/16 – 1/80 = 1/20 Inlet tap fills the tank in = 20 hours Inlet tap fills water at the rate of 8 litres a minute. Capacity of tank = 20 * 60 * 8= 9600 litre
Description : Three consecutive numbers such that twice the first, 3 times the second and 4 times the third together make 182. The numbers in question are 1. 18, 22 and 23 2. 18, 19 and 20 3. 19, 20 and 21 4. 20, 21 and 22 5. 21, 22 and 23
Last Answer : Answer- 3( 19,20,21) Explanation:- let number be x,x+1,x+2 2x + 3(x+1)+4(x+2)=180 x=19 so numbers are 19,20,21
Description : A pump can fill a cistern in 12 hrs. After half the cistern is filled, 3 more similar pumps are opened. What is the total time taken to fill the cistern completely? A) 8 hrs B) 4 hrs C) 2hrs D) 7.5 hrs
Last Answer : D Time taken by 1 pump to fill tha half tank = 6 hrs Part filled by the 4 pumps in 1 hr = 4 * 1/12 =1/12 =>1/3 Remaining part = (1 – 1/2)= 1/2 Therefore 1/3 :1/2 :: 1:x X=1.5 hrs So total time takem = 6hrs + 1.5 hrs = 7.5 hrs.
Description : Three pipes A, B and C can fill a tank in 6 hours. After working at it together for 2 hours, C is closed and A and B can fill the remaining part in 7 hours. The number of hours taken by C alone to fill the tank is: a) 10 b) 14 c) 12 d) 13 e) 15
Last Answer : (A+B+C) - (A+B) (A+B+C) =1/6 and (A+B+C) in 2hrs=2/6 and remaining part 1-2/6=2/3. So (A+B) in 7 hrs is 2/ (3*7) =2/21. 1/6-2/21=1/14 so answer is 14. Answer: b)
Description : A tap can fill a bunker in 4 hours. After half the bunker is filled, three more similar tap are opened. What is the total time taken to fill the bunker completely? A) 3 hours B) 2.5 hours C) 5 hours D) 4.2hours
Last Answer : B In One hour tap can fill = 1/4 Time is taken to fill half of the bunker = 1/2 * 4= 2hours Part filled by four taps in one hour = (4*1/4) = 1 Required Remaining Part = 1/2 Total time = 2+ 1 /2=2.5 hrs
Description : A pipe can fill a tank in 4 hours and another pipe can empty the same tank in 6 hours. When both the pipes are opened simultaneously, the part of tank
Last Answer : A pipe can fill a tank in 4 hours and another pipe can empty the same tank in 6 hours. When both the ... the part of tank filled in 1 hour is ..
Description : Three pumps, M, N and O are opened to fill a tank such that M and N can fill the tank alone in 18 min. and 23 min. respectively and O can empty it in 15 min. After 3 minutes the emptying pipe is closed. In how many minutes the tank will be full in this way? A) 20 B) 25 C) 18 D) 12
Last Answer : D Let the tank full in x minutes, then M and N opened for x minutes and O for 3 minutes. (1/18 + 1/23)*x – (1/15)*3 = 1 (23+18/414)X=1+1/5 Solve, x = 12
Description : A tube can fill a cistern in 18hrs.After half the cistern is filled, three more similar tubes are opened. What is the total time taken to fill the cistern completely ? A) 9hrs 52min B) 10hrs 15 min C) 9hrs 45 min D) 10hrs 30min
Last Answer : Time taken to fill half of the cistern = 18/2 = 9 hrs After half the cistern is filled , three more similar tubes are opened. We know that one tube can in 18 hrs can fill = V litres(i.e. fully fill a cistern) ... V/2 will be 2 hrs 15 min Total time = 9 hrs + 2 hrs + 15 min = 11 hrs 15 min
Description : A tank has two faucet which fill it in 15 mins and 18 mins respectively. There is also a waste faucet in the tank. When all the 3 are opened the empty tank is full in 25 mins. How long the waste faucet take to empty the full tank? A) 450/17 mins B) 450/28 mins C) 450/37 mins D) 450/22 mins
Last Answer : C Work done by the waste faucet in 1 minute =>1/25 – (1/15 + 1/18) =>1/25 – (6+5/90) = 1/25 – 11/90 => - 37/450 Here negative sign means emptying Therefore waste faucet will empty the full tank in 450/37 mins.
Description : The average age of four boys, five years ago was 9 of all the five is 15 years. The present age of the new boy is 1. 22 years 2. 24 years 3. 21 years 4. 18 years 5. 19 years
Last Answer : 5; Five years ago the average age of 4 boys = 9 years The present average age of 4 boys = 9+5 = 14 So the present age of new boys = 15 + 4 x 1 = 19 years
Description : What is the total number of literate people in city 'A'? 1) 21.62 lakh 2) 22.18 lakh 3) 23.94 lakh 4) 24.63 lakh 5) 25.02 lakh
Last Answer : 3) 23.94 lakh
Description : Two pipes fills a tank in 12 hours and 15 hours respectively while a third pipe empties the tank in 18 hours. !f all three pipes operate simultaneously, in what time will the tank be full? a) 10 hours b) 10 10/17 hours c) 11 hours d) 9 hours e) 12 1/17 hours
Last Answer : b) 10 10/17 hours
Description : Two taps can fill a bunker in 40 and 48 mins respectively and a waste tap can empty 6 gallons per minute. All the 3 taps working together can fill the bunker in 30 mind. The capacity of the bunker is. A) 480 B) 480 C) 680 D) 780
Last Answer : A Work done by the waste tap in 1 min = 1/30 – (1/40 + 1/48) = 8 – (6+5)/240 = 8-11/240 = -3/240 = -1/80 (negative sign means emptying) Volume of 1/80 part = 60 gallons Volume of whole = (6*80) = 480 gallons
Description : Two faucet A and Bcan fill a cistern in 6 hours and 2 hours respectively. If they are opened on alternate hours and if faucet A is opened first, in how many hours will the cistern be full? A) 4 hours B) 5 hours C) 7 hours D) 6 hours
Last Answer : A Faucet A can fill = 1/6 faucet B can fill = 1/2 For every two hour, 1/6 + 1/2 = 1+3/6 =>4/6=2/3 Part filled Total filled in 3 hours = 2/3+1/6= 5/6 In next hour it will be fille full. So total time will be 4 hours.
Description : 3 faucet A,B,C can fill a cistern from empty to full in 45mins, 35mins, and 25 mins respectively. When the cistern is empty all the 3 faucets are opened. A,B,c discharge chemical solutions A,B,C respectively. What is ... the liquid in the tank after 5 mins? A) 63/143 B) 72/151 c) 67/173 D) 81/167
Last Answer : A Part filled by (A+B+C) in 5 mins = 5(1/45 +1/35 + 1/25) = 5 (35+45+63/1575) = 143/315 Part filled by c in 5 mins = 5/25 = 1/5 Required ratio = 1/5 * 315/143 =63/143.
Description : A cistern is filled by three faucets with uniform flow. The first two faucets operating simultaneously fill the cistern in the same during which the cistern is filled by the third faucet alone. The second faucet fills the cistern ... by the first faucet is? A) 6 hrs B) 10 hrs C) 15 hrs D) 30 hrs
Last Answer : C Suppose, first faucet alone takes x hours to fill the cistern. Then, second and third faucets will take (x - 5) and (x - 9) hours respectively to fill the cistern. 1/x + 1/(x - 5) = 1/(x - 9) (2x - 5)(x - 9) = x(x - 5) x2 - 18x + 45 = 0 (x- 15)(x - 3) = 0 => x = 15
Description : Four pipes can fill a reservoir in 15, 20, 30 and 60 hours respectively. The first one was opened at 6 AM, second at 7 AM, thir da t 8 AM and the fourth at 9 AM. When will the reservoir be filled ? (A) 11 AM (B) 12 Noon (C) 1 PM (D) 1:30 PM
Last Answer : Answer: C
Description : A large cistern can be filled by 2 pipes P & Q in 120 mins and 80 mins respectively. How many mins will it take to fill the cistern from empty state if Q is used for half the time and P & Q fil it together for the other half? A) 2hrs B) 1hr C) 3hrs D) 4hrs
Last Answer : B Part filled by (P+Q) in 1 min = 1/120 + 1/80 =2+3/240 = 5/240 = 1/48 Suppose the cistern is filled in x mins then, x/2 (1/48 + 1/80) = 1 x/2(5+3/240)=1 8x/480 = 1 x=480/8 x= 60 mins or 1 hr
Description : A tank has two inlet pipes, A and B, which can fill the tank in 12 hours and 18 hours respectively, and an outlet C which can empty the tank in 9 hour
Last Answer : A tank has two inlet pipes, A and B, which can fill the tank in 12 hours and 18 hours ... time taken right from the start to fill the tank.
Description : A Bunker has a leak which would empty the completely filled bunker in 20 hours. If the bunker is full of water and a tap is opened which admits 4 litres of water per minutes in the bunker, how many litres does the bunker holds? A) 2400 B) 4500 C) 4800 D) 7200
Last Answer : C Leak emptied the bunker per hour = 100/20 = 5% of water per hour; Quantity of water emptied per hour = 4*60 = 240; Thus, 5% = 240 liter; Hence, capacity of water, 100% = 240*100/5= 4800 liter.
Description : Two pipes can fill a tank in 20 and 24 minutes respectively and another pipe can empty 3 gallons per minute. All the three pipes working together can fill the tank in 15 minutes. The capacity of the tank in gallons is: a)100 b)110 c)120 d)140
Last Answer : c)120
Description : 3 faucet P,Q & R can fill a cistern in 12 hrs. After working together for 4hrs, R is closed P and Q can fill the remaining part in 14 hrs. The number of hrs taken by R alone to fill the cistern is. A) 18 hrs B) 20 hrs C) 28hrs D) 30hrs
Last Answer : C Part filled in 4 hrs = 4/12 = 1/3 Remaining part = 2/3 (P+Q)’s 14 hrs work = 2/3 (P+Q)’s 1 hr work = 2/ 3 *14 = 1/21 R’s 1 hr work = (P+Q+R)’s 1 hr work – (P+Q)’s 1 hr work = 1/12 – 1/21 = 7-4/84 = 3/84 = 1/28 R alone can fill the tank in 28 hrs.
Description : Two tube A and B can fill a cistern in 48 mins and 64 mins. If both the tubes are opened simultaneously, after how much time B should be closed so that the cistern is full in 36 minutes? A) 20 mins B) 16mins C) 22mins D) 14mins
Last Answer : B Let B be closed after ‘x’ mins. Then part filled by (A+B) in x mins + part filled by A in (36 – x) mins = 1 Therefore x(1/48 + 1/64) + (36 – x)* 1/48 = 1 7x/192 + 36 – x/48 = 1 7x + 4(36-x)/192 = 1 7x+144 – 4x = 192 3x = 48 =>x = 16 Here B must be closed after 16 mins.