Frances can complete a job in 12 hours, and Joan can complete the same job in 8 hours.
Frances starts the job at 9 a.m., and stops working at 3 p.m. If Joan starts working at 4 p.m. to
complete the job, at what time is the job finished?
(A) 6 p.m.
(B) 7 p.m.
(C) 8 p.m.
(D) 10 p.m.
(E) 12 p.m.

• Answer is (C): 8 p.m. Half of the work is done by Frances, as he works for 6 hours. For, half of the work to be done, Joan takes 4 hours. So, job will be finished by 8 p.m.
• 14 years agoHelpfull: Yes(2) No(0)
• 8p.m.
  F J F J
  hr 12 8 6 12/3 = 4
  work=LCM(hr)=24
  rate 24/12=2 24/8=3 2 3
  =====================================================
  work = 12 remaining = 12
  
• 8 years agoHelpfull: Yes(0) No(0)