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SSC CPO Basic Time & Work

Study Material — 1 PYQs (2020–2020) · Concept Notes · Shortcuts

SSC CPO Basic Time & Work is a frequently tested subtopic — 1 previous year questions from 2020–2020 papers are included below with concept notes, key rules and shortcut tricks.

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Previous Year Questions

SSC CPO Basic Time & Work — Past Exam Questions

1 questions from actual SSC CPO papers · all shown free · click option to reveal solution

Exam Q 12020Previous Year Pattern

A can do 1/3 of a work in 5 days. In how many days can A complete the entire work?

Concept Notes

Basic Time & Work— Rules & Concept

💡

Core Concept

Read this first — the foundation of the topic

→Core Concept

Work is always considered as 1 unit (complete job). If A can complete work in 10 days, A's rate of work is 1/10 per day. This means A completes 1/10th of the total work each day

💡Key Rules

Work = Rate × Time. If multiple people work together, their rates add up. Total work is always 1 unit. Rate of work = 1/Time taken to complete the job

🔑Basic Formulas

- If A completes work in 'a' days, A's one day work = 1/a - If A and B together complete work in 'd' days, (1/a + 1/b) = 1/d - Time taken by A and B together = (a × b)/(a + b) days - If A completes work in 'x' days and B in 'y' days, working together they complete in xy/(x+y) days

📊

Exam Patterns

What examiners ask — read before attempting PYQs

📋Common patterns include

two people working together, one person leaving midway, comparing efficiencies, and alternative work scenarios

⚡Shortcut Trick - LCM Method

Take LCM of all time periods given. This becomes total work. Then find individual rates by dividing LCM by individual time. This eliminates fractions and makes calculations faster

✏️Worked Example 1

1

A's one day work = 1/12

2

B's one day work = 1/18

3

Combined one day work = 1/12 + 1/18 = (3+2)/36 = 5/36

4

Time taken together = 36/5 = 7.2 days Alternative (Shortcut): Time = (12 × 18)/(12 + 18) = 216/30 = 7.2 days Worked Example 2: A and B together can complete work in 6 days. A alone can complete it in 10 days. In how many days can B alone complete the work?

1

Combined one day work = 1/6

2

A's one day work = 1/10

3

B's one day work = 1/6 - 1/10 = (5-3)/30 = 2/30 = 1/15

4

B alone can complete work in 15 days Shortcut Formula: If A and B together complete work in T days and A alone in A days, then B alone takes: B = (A × T)/(A - T) days Applying: B = (10 × 6)/(10 - 6) = 60/4 = 15 days Most Common Trap: Students often add time instead of adding rates. Remember - when people work together, their RATES add up, not their TIME. If A takes 4 days and B takes 6 days, together they DON'T take 4+6=10 days. Instead, calculate 1/4 + 1/6 to find combined rate

⚠️Another Major Mistake

Forgetting that work is always 1 unit. Students sometimes assume work quantity changes, leading to wrong calculations. Always treat complete work as 1 unit regardless of the scenario

⚡Efficiency Trick

If A is twice as efficient as B, then A takes half the time B takes. If A:B efficiency ratio is 2:3, then their time ratio is 3:2 (inverse relationship)

→Negative Work Concept

Sometimes one person does work while another undoes it (like filling and emptying a tank). In such cases, subtract the rates instead of adding them.

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SSC CPO Basic Time & Work

SSC CPO Basic Time & Work — Past Exam Questions

Basic Time & Work— Rules & Concept

Key Points to Remember

Exam-Specific Tips

60-Second Revision — Basic Time & Work