GIVEN: 1 man or 2 women or 3 kids can complete a piece of work in 66 days each. FORMULA USED: Time = Work/Efficiency CALCULATION: Let the efficiency of man, woman and kid be m, w and k According to the question, 1m = 2w = 3k Ratio of efficiencies of men, women and kid is 6 : 3 : 2 Total work = 6 × 66 = 396 Work done be all together in 1 day = 6 + 3 + 2 = 11 units Required number of days = 396/11 = 36 days ∴ If 1 man, 1 woman, and 1 kid work together then in 36 days the work will be completed. [ alt="Shortcut trick" src="//storage.googleapis.com/tb-img/production/20/08/Shortcut%20trick.GIF" style="width: 149px; height: 33px;"> Suppose total work is 66 units. Efficiency of a man = 66/66 = 1 Efficiency of a women = 66/(66 × 2) = 1/2 Efficiency of a kid = 66/(66 × 3) = 1/3 Time in which all of them will complete the work = 66/(1 + 1/2 + 1/3) ⇒ 66/(11 / 6) ⇒ 36 days ∴ If 1 man, 1 woman, and 1 kid work together then in 36 days the work will be completed.