Question

One pipe can fill an empty cistern in 4 hours while another can drain the cistern when full in 10 hours. Both the pipes were turned on when the cistern was half-empty. How long will it take to fill the cistern completely?

• A. 6 hours 40 minutes
• B. 5 hours 30 minutes
• C. 4 hours 20 minutes
• D. 3 hours 20 minutes

Answer 1

Answer: (D)