Question

A pipe can fill an empty cistern in 7.8 hours while another can empty the cistern when full in 19.5 hours. Both the pipes were turned on when the cistern was half-empty. How long will it take for the cistern to be full?

• A. 5.2 hours
• B. 3.9 hours
• C. 7.8 hours
• D. 6.5 hours

Answer 1

Answer: (D)