Three identical pipes fill a tank in 12 hours. After 4 hours one pipe is closed. What is the total time taken to fill the tank?
Correct answer C. 16 hours
Explanation
In 4 hours one-third is filled. Each pipe fills 1/36 per hour, so two pipes fill the remaining 2/3 in 12 hours. Total = 16 hours.
Answer checked How we write and check questions
Discussion