Amit is five times as efficient as Deepak and twice as efficient as Farhan. If Deepak takes 60 days to finish some work, then find the time taken by Amit and Farhan to do the same work together.

Since, Amit is five times as efficient as Deepak, he will take one-fifth the time taken by Deepak to finish the work. So, time taken by Amit to do the work = 60 ÷ 5 = 12 days And, Amit is twice as efficient as Farhan, so Farhan will take double the time taken by Amit. So, time taken by Farhan to do the work = 2 × 12 = 24 days Let the total work be '24x' units. So, efficiency of Amit = 24x ÷ 12 = '2x' units/day And, efficiency of Farhan = 24x ÷ 24 = 'x' units/day So, required time = 24x ÷ (2x + x) = 8 days Hence, option b.