Work per day

If a job takes n days, you do 1/n of it each day. Working with rates makes these sums easy.

• 10 days for a job → 1/10 of the job per day.
• Work done = rate × time.
• More workers, fewer days: workers × days stays the same.

Example: 6 workers take 10 days: 60 worker-days. 15 workers need 60 ÷ 15 = 4 days.

Remember: Turn every time into a rate (job per day).

Common mistake: Averaging the days instead of adding the rates.