Two pipes X and Y fill one-third of the tank in 12 hrs and 15 hrs…
2016
Two pipes X and Y fill one-third of the tank in 12 hrs and 15 hrs respectively. If both pipes are opened simultaneously, how much time will be taken to fill the tank?
- A.
20 hours
- B.
10 hours
- C.
15 hours
- D.
12 hours
Attempted by 4 students.
Show answer & explanation
Correct answer: A
Pipe X fills one-third of the tank in 12 hours, so it fills the full tank in 36 hours. Pipe Y fills one-third in 15 hours, so it fills the full tank in 45 hours. Together their rate is 1/36 + 1/45 = 1/20 tank per hour, so they fill the tank in 20 hours.