Two water pipes can fill a tank in 10 minutes and 15 minutes, respectively, if…
2020
Two water pipes can fill a tank in 10 minutes and 15 minutes, respectively, if each of them is used separately. If both the pipes are used to fill the tank simultaneously, how long will it take to fill the tank?
- A.
6 minutes
- B.
8 minutes
- C.
7.5 minutes
- D.
9 minutes
Attempted by 7 students.
Show answer & explanation
Correct answer: A
Pipe 1 fills the tank in 10 minutes, so its rate is 1/10 tank per minute.
Pipe 2 fills the tank in 15 minutes, so its rate is 1/15 tank per minute.
Together, their rate = 1/10 + 1/15 = 3/30 + 2/30 = 5/30 = 1/6 tank per minute.
If 1/6 of the tank is filled in one minute, the full tank will be filled in 6 minutes.
Therefore, the correct answer is 6 minutes.