Amit is five times as efficient as Deepak and twice as

Solution

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.