Pipes A and B can fill a tank in 12 hours and 16 hours respectively and pipe C can empty the full ta...........

Quantitative Aptitude (CGL) Pipes&cistern

Pipes A and B can fill a tank in 12 hours and 16 hours respectively and pipe C can empty the full tank in 24 hours. All three pipes are opened together, but after 4 hours pipe B is closed. In how manyhours, the empty tank will be completely filled?

This questions was previously asked in

SSC CGL 23rd August 2021 Shift-1

View All ssc Previous Year Papers

छोटे Courses बड़े Results

Master Pipes&cistern

Prepare through Micro-courses

Try Now

Explanation:

Correct Option is 1 - 18 hours

Time taken to fill a tank by Pipe B = 16 hours
Time taken to empty a tank by Pipe C = 24 hours
Formula used:
Work = Efficiency x Time
Calculation:
LCM of 12, 16 and 24 is 48
Efficiency of A to fill the tank = (48/12) = 4 hours/day Efficiency of B to fill the tank (48/16) = 3 hours/day Efficiency of C to empty the tank = (48/24) = - 2 hours/day
All three pipes opened together for 4 hours = [(4 + 3 − 2) x 4] ⇒ (5 × 4) = 20 unit
Remaining unit = (48-20) = 28 unit
Time taken by A and C together = [28/(4-2)]
⇒ (28/2) = 14 hours
Now,
Total time is taken to fill the empty tank = (14 + 4) hours
⇒ 18 hours
The required time is 18 hours