SSC CGL Time and Work Shortcuts with Solved Questions

Time and Work is 1–2 questions in every SSC and bank paper and the same method solves pipes-and-cisterns. Forget fractions — use the LCM method.

LCM method

1. Take total work = LCM of the days given.
2. Efficiency (work per day) = total work / days.
3. Combine efficiencies; time = total work / combined efficiency.

Formulas

• Efficiency ∝ 1/time. If A is twice as efficient as B, A takes half the time.
• Work and wages: share ∝ work done = efficiency × days worked.
• M₁D₁H₁/W₁ = M₂D₂H₂/W₂ (men-days-hours)

Solved questions

1. A does a job in 12 days, B in 15. Together? LCM 60; efficiencies 5 + 4 = 9 → 60/9 = 6⅔ days
2. A and B together in 6 days, A alone in 10 → B: 30 units, 5 − 3 = 2/day → 15 days
3. A, B, C in 10, 12, 15 days; all three: LCM 60; 6 + 5 + 4 = 15 → 4 days
4. A works 2 days then leaves; A: 8 days, B: 12 days. B finishes? Total 24; A does 6; B does 18 at 2/day → 9 days
5. Pipe fills in 6 h, another empties in 9 h; both open: LCM 18; 3 − 2 = 1 → 18 h
6. A is 50% more efficient than B; B takes 15 days → A takes 10 days
7. Wages ₹1200 for work done by A (6 days) and B (9 days), A twice as fast as B → ratio 12 : 9 → A gets ₹686
8. 20 men in 30 days; after 10 days 5 leave → remaining 400 man-days / 15 men = 26.67 days more
9. A and B alternate, A starts; A: 10 days, B: 15 → 2-day cycle does 5 units of 30 → 12 days
10. Two pipes fill in 12 and 16 h; leak empties full tank in 24 h → 4 + 3 − 2 = 5 → 48/5 = 9.6 h
11. A in 8 days, B in 10; both work, A leaves 2 days before end → 40 units; B alone 8 units in 2 days; rest 32 at 9/day → 3.56 + 2 = 5.56 days
12. 12 women or 18 children in 15 days; 8 women + 6 children? Woman = 1.5 child → 21 child-units → 270/21 = 12.86 days
13. A does 1/3 in 5 days → whole in 15 days
14. B does 60% of a job in 12 days → whole in 20 days
15. Three taps: 10, 15 min fill, 20 min empty; all open → 6 + 4 − 3 = 7 → 60/7 ≈ 8.57 min

Common mistakes

• Adding days instead of efficiencies
• Forgetting negative efficiency for emptying pipes
• Not tracking who worked how many days in wage problems

Related: Profit and loss tricks.

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Frequently asked questions

Which exams is this SSC CGL Time and Work Shortcuts with Solved Questions guide useful for?

SSC CGL, CHSL, MTS, GD, RRB NTPC and Group D, IBPS and SBI PO/Clerk, state PSC and other exams with a similar syllabus.

How much practice is needed for SSC CGL Time and Work Shortcuts with Solved Questions?

Solve 20–30 questions daily for one to two weeks with a timer. Track the time per question and your accuracy; move on once accuracy is above 90 percent.

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