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Quantitative Aptitude / Arithmetic

Time & Work Efficiency Mechanics

High (2 questions in almost every competitive shift)

Concept Overview

Time and Work questions deal with relationships between number of workers, their efficiencies, and the total work completed. Using LCM of time durations to represent 'Total Work Units' is the fastest method to solve these questions instead of traditional fraction equations.

Exam Relevance

Tested heavily in SSC CGL/CHSL Tier 1 & 2, RRB NTPC, State Police Constable, and SBI/IBPS Clerk exams.

Key Formulas & Shortcuts

  • Work Done = Efficiency * Time Taken
  • If A takes x days and B takes y days, Total Work = LCM(x, y).
  • Man-Days Formula: (M1 * D1 * H1) / W1 = (M2 * D2 * H2) / W2

Common Weaknesses & Mistakes

1

Inverting efficiency: Confusing time taken with efficiency (less time = higher efficiency).

2

Incorrect negative work calculations in Pipe & Cistern leaks.

3

Adding days directly: Adding individual days taken instead of calculating daily work outputs.

Ready to check your subject readiness?

This will pre-configure your **Quantitative Aptitude Diagnostic Test**. You will bypass selection screens and land directly on the start screen to begin a 40-question subject-level diagnostic test.