P can complete a work in 12 days working 8 hours a day. Q can complete the same work in 8 days working 10 hours a day. If both P and Q work together, working 8 hours a day, in how many days can they complete the work?
Answer: A
Total hours taken by P = \(12 \times 8 = 96\) hours. Total hours taken by Q = \(8 \times 10 = 80\) hours. P's 1 hour work = 1/96. Q's 1 hour work = 1/80. Together, their 1 hour work = \(1/96 + 1/80 = (5+6)/480 = 11/480\). They will take 480/11 hours to complete the work. Since they work 8 hours a day, the number of days = \((480/11) / 8 = 60/11 = 5 \frac{5}{11}\) days.