Time & Work Set
TRICK–1 : Men–Days–Work (Basic Rule)
Rule
Men × Days = Constant Work
Ex 1. 12 men can do a work in 20 days. How many days will 5 men take ?
Soln
12×20 = 5×A
A = 240/55 = 48
Ans: 48 days
Ex 2. 15 boys can do a work in 20 days. How many days will 10 boys take? (Boys Problem)
Soln
15×20 = 10 × A
Ans: 30 days
TRICK–2 : Men–Women–Work
Rule: First convert all workers into one unit using efficiency.
Ex 3. 1 Man = 2 Women, 5 men + 4 women can do work in 36 days. How many days will 4 men take ?
Soln
5M + 4W = 5M + 2M = 7M
7 × 36 = 4 × A
Ans: 63 days
TRICK–3 : Efficiency ↔ Time
Rule: Efficiency ∝ 1/Time
Ex 4. Efficiency of A : B = 3 : 2 Find time ratio.
Soln
Time = 2:3
Ans: 2 : 3
TRICK–4 : Wages & Efficiency
Rule: Wages ∝ Efficiency
Ex 5. A, B, C complete a work together. Efficiency ratio = 15 : 12 : 10.Total wages = ₹7400. Find B’s share.
Soln
Total ratio = 15+12+10 = 37
B = 12/37×7400
B = ₹2400
Ans: ₹2400
TRICK–5 : Given Time of Each, Find Wages
Ex 6. A works 15 days, B works 12 days, C works 10 days. Total wages = ₹7400. Efficiency same.
Soln
Ratio = 15:12:10
Sum = 37
A = 15/37×7400=₹3000
Ans: ₹3000