Two pipes p and q can fill an in 15 minutes and20 minutes respectvely, while the third pipeC can empty the cistern in 30mins. If the three pipes are opened at a time. How long it will take to empty the tank? a) 12hrs b) 13hrs c) 10hrs d) 11hrs
Answers
Answer:
Step-by-step explanation:
Pipes P and Q can fill the cistern in 1 minute
= 1/15 + 1/20= (4+3)/60= 7/60
They can fill the cistern in 5 minutes
= 7/60×5 = 35/60= 7/12
Remaining 5/12 part of the cistern would-be filled by pipe Q with a speed of 1/20 per minute
= 5/12÷1/20= 5/12×20= 25/3 minutes
Pipe Q would take to fill 5/12 cistern in
8 minutes and 20 seconds
Answer:
12 min is your answer
Step-by-step explanation:
work done by p in 1 min=1/15
work done by q in 1 min=1/20
work done by c in 1 min=1/30
work done by all in 1 min = 1/15 + 1/20 - 1/30
4/60 + 3/60 - 2/60
7/60 - 2/60
5/60
work will be done in 60/5min = 12 min
please subscribe my channel lucifer classes