8 identical machines, working alone and at their constant rates, take 6 hours to complete a job lot. How long would it take for 4 such machines to perform the same job?	Choose the correct option
A) 2.25 hours  B) 8.75 hours  C) 12 hours  D) 14.25 hours  E) 16 hours

Rationale: let each machine do 1 unit of work for 1 hour 8 machines - - > 8 units of work in 1 hour for 6 hours = 8 * 6 = 48 units of total work is done . now this 48 units of total work must be done by 4 machines 4 units of work ( 4 machines ) - - - > 1 hour for 48 units of work 4 * 12 - - - > 1 * 12 hours c 12 hours
Answer: C