Time & Work
🔒 Log in to trackRates, LCM units and the men-days chain solve nearly every question: combined work, efficiency ratios, pipes and cisterns, mid-work join/leave, alternate days, provisions and wages. One slot is near-guaranteed in Tier 1, with staged pipe problems and wage splits rising in Tier 2.
One page per subtopic: detailed notes, every question type, formulas, tricks and practice sets.
Every formula on one printable page, grouped by subtopic.
5 exam-level questions worked step by step.
61 questions — untimed practice or a timed test with analysis.
Track record in the exam
Questions per shift in recent SSC CGL papers.
Test difficulty mix (61 questions)
Question patterns exams keep repeating
Taken from previous-year papers. If a pattern is marked "very common", expect to see it in your exam.
Two or three people working together
very commonEach person's time alone is given. Asks the time working together.
Take a total that all times divide into (the LCM) as the job size.
Find each person's work per day and add them.
A can finish a job in 15 days and B in 10 days. How long will they take together?
Job = 30 units
A does 30 ÷ 15 = 2 a day, B does 30 ÷ 10 = 3 a day
Together = 5 a day
Time = 30 ÷ 5 = 6 days
Pipes and tanks
very commonPipes fill a tank and another pipe empties it. Asks the time to fill.
Filling pipes count as +, emptying pipes as −.
Add them up to get the net work per hour.
A pipe fills a tank in 12 hours. Another empties the full tank in 24 hours. With both open, how long to fill?
Tank = 24 units
Filling: 24 ÷ 12 = +2 an hour. Emptying: 24 ÷ 24 = −1 an hour
Net = 2 − 1 = 1 an hour
Time = 24 hours
"Twice as fast" comparisons
common"A is twice as efficient as B" or "A is 50% more efficient", with a total time given.
Give the slower worker 1 unit a day. The faster gets 2 (or 3, ...).
Total job = units a day together × days.
A is twice as efficient as B. Together they finish a work in 18 days. How long does B alone take?
B does 1 unit a day, A does 2
Together 3 a day, so job = 3 × 18 = 54 units
B alone = 54 ÷ 1 = 54 days
Someone leaves or joins in the middle
commonOne person works a few days and then leaves (or joins late). Asks the time left.
Work done = work per day × days.
Take it off the job. The rest goes to whoever is left.
A can do a work in 12 days and B in 18 days. A works 3 days and leaves. How long does B take to finish?
Job = 36 units. A does 3 a day, B does 2 a day
A in 3 days: 3 × 3 = 9 units
Left: 36 − 9 = 27 units
B finishes in 27 ÷ 2 = 13.5 days
Working on alternate days
commonA and B work one day each, turn by turn. Asks when the job is done.
Work out what one full round (2 days) completes.
Count the rounds, then check any leftover day.
A can do a job in 3 days and B in 6 days. They work on alternate days, A first. When is it done?
Job = 6 units. A does 2 a day, B does 1 a day
One round of 2 days = 2 + 1 = 3 units
6 units needs 2 rounds
2 rounds = 4 days
Men, days and hours
commonThe same work is done in two situations with different men, days or hours per day.
Find the total man-hours for the first case.
Divide by the men and hours per day of the second case.
12 men working 8 hours a day finish a work in 15 days. In how many days will 18 men working 10 hours a day finish it?
Total work = 12 × 8 × 15 = 1440 man-hours
Per day now = 18 × 10 = 180 man-hours
Days = 1440 ÷ 180 = 8 days
Food for a group of people
commonFood lasts some days for some people. Men join or leave later. Asks how long the rest lasts.
Food in "man-days" = men × days.
Remove what is eaten, then divide by the new number of men.
A fort of 400 men has food for 25 days. After 5 days, 100 more men join. How long does the food last now?
Food left after 5 days = 400 × 20 = 8000 man-days
Men now = 400 + 100 = 500
Days = 8000 ÷ 500 = 16 days
Sharing the pay
commonSome people do a job together and get a total payment. Asks one person's share.
Share the pay in the ratio of work each did.
With equal days, that is the ratio of their daily work.
A and B together earn ₹600. A alone can do the job in 10 days and B in 15 days. What is A's share?
Job = 30 units. A does 3 a day, B does 2 a day
Ratio A : B = 3 : 2
A's share = 3/5 of 600 = ₹360