| # | 📌 Concept / Scenario | 📝 Formula |
|---|---|---|
| 1 | 🛠️ Basic Work Formula | |
| 2 | 📉 Rate of Work (Efficiency) | |
| 3 | 🗓️ One Day’s Work | If a person can do a piece of work in n days, then their 1 day’s work = 1/n |
| 4 | 🏁 Total Time Taken | If a person’s 1 day’s work is 1/n, then total time to finish the work = n days |
| 5 | 🤝 Working Together (2 People) | If A does a work in x days and B in y days, together they take: xy/x+ydays |
| 6 | 🤝 Working Together (3 People) | If A takes x days, B takes y days, and C takes z days, together they take: xyz/(xy+yz+zx) days |
| 7 | ⚖️ Efficiency & Time Ratio | If A is 3 times as good a workman as B, then: Ratio of Work done by A and B = 3 : 1 Ratio of Time taken by A and B = 1 : 3 |
| 8 | 👥 Men, Days, Work (MDH Rule) | If men do work in days, and men do work in days: M1×D1/W1=M2×D2/W2 |
Key Points to Remember
- Time and efficiency are inversely proportional (More efficient workers take less time).
- When calculating work, the “Total Work” is usually assumed to be 1 unit (unless otherwise specified).
- If someone leaves the work midway, calculate the total work done until they left, subtract it from 1 (the whole work), and find how long the remaining person will take to finish the rest.
