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A tank can be filled by one tap in 10 minutes and by another in 30 minutes. Both the taps are kept open for 5 minutes and then the first one is shut off. In how many minutes more is the tank completely filled? |
| A) 5
B) 7.5
C) 10
D) 12 Correct Answer : 10 Explanation :
In 5 minutes work done by both pipes is = 5*(1/10 + 1/30) After 5 min first tap is closed, So, remaining work done by second tap is = 30*(1/3) = 10 |
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Three pipes A, B and C together can fill a cistern in 6 hours. After working together for 2 hours, C is closed and A and B fill the remaining cistern in 8 hours. Then the time in which the cistern can be filled by pipe C alone will be: |
| A) 11 hours
B) 9 hours
C) 12 hours
D) 10 hours
Correct Answer : 12 hours Explanation : Three Pipes A,B and C together filled a tank in 6 hours A and B can fill remaining in 8 hours, (A + B)'s 8 hour's work = 2/3 Therefore C's 1 hour's work C alone can fill the tank in 12 hours |
Two pipes A and B can fill a cistern in 4 and 6 minutes respectively. If both the pipes kept turned on alternatively for one minute each starting from A, how long will it take to fill the cistern? |
| A) 3(3/7) minutes
B) 6 minutes
C) 4(2/3) minutes
D) 6(6/7) minutes
Correct Answer : 4(2/3) minutes Explanation : As the pipes are operating alternatively for one minute, thus (A+B)'s 2 minutes job is =(1/4 +1/6) =5/12 Remaining part of cistern= 1 - 5/6 =1/6 Pipe A can fill 1/4 part of the cistern in 1 minute,and can fill 1/6 part of the cistern in = 4*(1/6) =2/3 minutes Total time taken to fill the Cistern = time taken to fill (5/6 part + 1/6 part) |
Pipe A can fill a tank in 45 hrs and pipe B can fill it in 36 hrs. If both the pipes are opened in the empty tank. In how many hours will it be full? |
| A) 10 hr
B) 15 hr
C) 20 hr
D) 28 hr
Correct Answer : 20 hr Explanation : If a pipe can fill a tank in x hours, then : part filled in 1 hour = 1/x Part filled A in 1 hr= (1/45) |
If a pipe fills a tank in 6 h, then what part of the tank will the pipe fill in 1 h? |
| A) 1/3
B) 1/6
C) 1/4
D) 1/5
Correct Answer : 1/6 Explanation : Let the pipe can fill a tank in x hours, then part filled in 1 hour = 1/x A pipe fills a tank in 6 h, then the part of tank filled in 1 h = 1/6 |
A tap can fill a tank in 16 minutes and another can empty it in 8 minutes. If the tank is already half full and both the taps are opened together, the tank will be ? |
| A) Filled in 12 min
B) Emptied in 12 min
C) Filled in 8 min
D) Emptied in 8 min
Correct Answer : Emptied in 8 min. Explanation : Let a pipe can fill a tank in x hours and another pipe can empty the full tank in y hours (where x > y), when opening both the pipes, the net part emptied in 1 hour = (1/y)-(1/x) |
One tap can fill a cistern in 2 hours and another can empty the cistern in 3 hours. How long will they take to fill the cistern if both the taps are opened ? |
| A) 5 hours
B) 6 hours
C) 7 hours
D) 8 hours
Correct Answer : 6 hours Explanation : Let a pipe can fill a tank in x hours, and another pipe can empty the full tank in y hours (where y> x), then on opening both the pipes, the net part filled in 1 hour = (1/x)-(1/y) Hence, time taken to fill the cistern = 6 hours |
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44 pipes can fill a large water tank in 27 hours. How many hours it take for 66 pipes to fill four such tanks ? |
| A) 72
B) 54
C) 63
D) 84
Correct Answer : 72 Explanation : 44 pipes => 27 hours Amount of work done is same for filling a pipe, So 44*27 = 66*X |