InterviewSolution
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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Three pipes A, B andC are attached to a tank. A and B can fill it in 20 and 30 minutes respectively while C can empty it in 15minutes. If A, B and C are kept open successively for 1 minute each how soonwill the tank be filled? |
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Answer» LCM of 15,20 and 30 is 60.so let the capacity of tank be 60 liters. A and B fill the tank at a rate of 3 liters per minute and 2 liters per minute. c empties the tank at a rate of 4 liters per minute. so if opened successfully for 1 minute each 1 liter will be filled in 3 minutes. so 55 liters will be filled in 55 x3=165 minutes , after the 165th minutetap A and B will fill 5 liters in 2 minutes. so total time taken =167 minutes = 2 hours and 47 minutes |
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| 2. |
A swimming pool is filled by three pipes withuniform flow. The first two pipes operating simultaneously fill the pool inthe same time during which the pool is filled by the third pipe alone. Thesecond pipe fills the pool 5 hours faster than the first pipe and 4 hoursslower than the third pipe. The time required by the first pipe is`6 h r s`b. `10 h r s`c. `15 h r s`d. `30 h r s` |
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Answer» Let `F=x hours``S=x-5 hours``T=x-9 hours`where, F stands for first pipe S for second and T for third pipe`1/x+1/(x-5) =1/(x-9)``(x-5+x)/(x(x+5))= 1/(x-9)``(x-9)(2x-5)=x(x-5)``2x^2-5x-18x + 45= x^2-5x``2x^2-18x+45 = x^2``x^2-18x+45=0``x^2-15x-3x+45=0``x(x-15)-3(x-15)=0``(x-15)(x-3)=0`Therefore,`x=15 or x=3` `x=3 hours` is not possible.Hence, time taken by First pipe, F `=15 hours`then time taken by S `=15-5=10 hours`and by T `=15-9= 6 hours` |
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