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Time & Work

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Quantitative Aptitude – Time & Work

Calculate work done collectively or individually using rate × time relations.

1. Basic Formula

Work = Rate × Time. If A does a job in a days, A’s rate = 1/a job per day.

2. Combined Work

If A and B work together, rate = 1/a + 1/b. Total time = 1/(rate).

3. Pipes and Cisterns

Inlet adds, outlet removes. Net rate = sum(inlet rates) − outlet rate.

4. Quick Tips

  • Convert all into “job/day” units before combining.
  • For group work add rates; for differences subtract them.

5. Common Errors

  • Adding times instead of rates.
  • Misplacing sign for outflow in pipe problems.

6. Revision Checklist

  • Practice combined work problems with varying rates.

Summary: Write individual rates, combine as needed, invert to get time. For pipes add inflow and subtract outflow rates, ensuring unit consistency.