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Time and Work CAT Questions with Video Solutions
Time and Work is one of the most common topics in the CAT Quant section. Usually, 1–2 questions are asked every year. These questions test your understanding of efficiency, combined work, and sometimes pipes and cisterns.
In this blog, we bring you important Time and Work CAT questions with step-by-step solutions. We have also added video explanations (if you embed them) and a PDF download so that you can practice easily.
Important Formulas for CAT Time and Work Questions
Before solving problems, it is important to know the basic formulas. These formulas will help you solve questions quickly:
| Concept | Formula | Example |
|---|---|---|
| Work Formula | Work = Rate × Time | If A finishes a job in 10 days, he does 1/10 work per day |
| Efficiency | Efficiency = 1 / Time taken | If A takes 20 days → efficiency = 1/20 |
| LCM Method | Take LCM of times as total work | A: 10 days, B: 15 days → Work = 30 units |
| Combined Work | 1/T(A+B) = 1/A + 1/B | A: 10 days, B: 15 days → Together = 6 days |
| Wages Rule | Wages ∝ Work done | If A:B = 2:3 efficiency → Wages = 2:3 |
| Pipes Rule | Inlet = positive, Outlet = negative | Inlet = 1/10, Outlet = -1/20 → Net = 1/20 |
👉 Tip: Always use the LCM method. It is much faster than dealing with fractions.
Common Mistakes to Avoid in Time and Work Questions
Students often make small mistakes that cost them marks. Be careful of these:
Mixing time and efficiency: If A takes fewer days, A is more efficient. Don’t confuse the two.
Dropping fractions too early: Always calculate till the last step before rounding off.
Forgetting sign in pipes questions: Remember: inlet = positive, outlet = negative.
Not using LCM method: Using fractions is slow. LCM saves time in exam.
Confusing wages and time: Wages are given in the ratio of efficiency, not the number of days.
Question 1
A tank is fitted with pipes, some filling it and the rest draining it. All filling pipes fill at the same rate, and all draining pipes drain at the same rate. The empty tank gets completely filled in 6 hours when 6 filling and 5 draining pipes are on, but this time becomes 60 hours when 5 filling and 6 draining pipes are on. In how many hours will the empty tank get completely filled when one draining and two filling pipes are on?
correct answer:- 10
Question 2
Amal can complete a job in 10 days and Bimal can complete it in 8 days. Amal, Bimal and Kamal together complete the job in 4 days and are paid a total amount of Rs 1000 as remuneration. If this amount is shared by them in proportion to their work, then Kamal's share, in rupees, is
correct answer:- 1
Question 3
Three machines, A, B and C can be used to produce a product. Machine A will take 60 hours to produce a million units. Machine B is twice as fast as Machine A. Machine C will take the same amount of time to produce a million units as A and B running together. How much time will be required to produce a million units if all the three machines are used simultaneously?
correct answer:- 2
Question 4
A company has a job to prepare certain number cans and there are three machines A, B and C for this job. A can complete the job in 3 days, B can complete the job in 4 days, and C can complete the job in 6 days. How many days will the company take to complete the job if all the machines are used simultaneously?
correct answer:- 2
Question 5
A can complete a piece of work in 4 days. B takes double the time taken by A, C takes double that of B, and D takes double that of C to complete the same task. They are paired in groups of two each. One pair takes two-thirds the time needed by the second pair to complete the work. Which is the first pair?
correct answer:- 4
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