Time and Work Questions for SBI CLERK

Core Concept: Work as a Rate

Think of work as filling a bucket. Each worker fills the bucket at a fixed rate per day. If A takes 10 days to fill it alone, A fills 1/10th of the bucket per day. Total work is always 1 complete job. The key insight is: Work Done = Rate x Time. Once you understand that work is just a rate problem, everything else follows naturally.

• If a person completes a job in N days, their 1-day work = 1/N
• Combined 1-day work of A and B = 1/A + 1/B
• Total days when working together = 1 divided by (combined 1-day work)
• Work Done = Efficiency x Number of Days
• Always check: does the question ask for days, fraction of work, or number of workers?

LCM Method: The Fast Track

Instead of fractions, assign the total work a number equal to LCM of all given days. Then each person's daily work becomes a whole number. This kills fraction arithmetic and saves 30-40 seconds per question. It is the most recommended technique for SBI Clerk speed.

• Step 1: Find LCM of all the days mentioned
• Step 2: Assign LCM as total work units
• Step 3: Each person's daily output = LCM divided by their individual days
• Step 4: Add daily outputs for combined work, then divide total units by combined output
• Works perfectly for 3 or more people too, unlike the two-person shortcut formula

Pipes and Cisterns

Pipes and Cisterns is just Time and Work with a twist in language. Inlet pipes fill the tank (positive work) and outlet pipes empty it (negative work). A pipe filling a tank in X hours does 1/X work per hour. An outlet pipe draining in Y hours does -1/Y work per hour. Everything else is identical to standard Time and Work.

• Inlet pipe = positive rate, outlet pipe = negative rate
• Net rate = sum of all inlet rates minus sum of all outlet rates
• If net rate is negative, tank empties — rephrase question as: how long to empty?
• When a leak is introduced, the effective time increases — if answer comes out longer, that is correct
• Leak questions often ask: how long will the full tank take to empty given both inlet and leak?

Work and Wages

When workers are paid for a job, wages are distributed in the ratio of work done (not time spent). Efficiency directly determines pay share. If A is twice as efficient as B, A gets twice the share of wages. This is a common twist in SBI Clerk Mains.

• Wages split in ratio of work done by each person
• Work done is proportional to efficiency x days worked by that person
• If all work for same number of days, split wages in ratio of their efficiencies
• If they work different days, calculate actual units each completes, then split

Men, Women, Children Variants

These questions give you the output rates of different categories and ask how many of one type are needed or how long a mixed group takes. Set up equations using 1-day work. Express all unknowns in terms of one unit. These appear more in Mains than Prelims.

• Find 1-day work of each category from given data
• Set up equation: (m x Man-rate) + (w x Woman-rate) = 1/Days
• Often two equations are given — solve simultaneously
• Watch out for questions where children do zero work — pure distractor

• Using the two-person shortcut (AxB)/(A+B) for three or more people — it only works for exactly two people.
• Forgetting to subtract work already done before calculating remaining time — always track what fraction is complete.
• In pipes, treating all pipes as positive — outlets must be subtracted, not added.
• Confusing efficiency ratio with time ratio — if A is 3 times more efficient than B, A takes 3 times LESS time, not more.
• In wage problems, splitting equally instead of by work ratio — wages follow effort, not headcount.

• RATE = 1/TIME: Think of a tap. A tap that fills in 5 hours pours 1/5th of the tank every hour. That image sticks.
• LCM = Total Work: Always give the job a name equal to LCM. It turns ugly fractions into clean whole numbers — no calculator needed.
• INLET plus, OUTLET minus: Remember I-P-O-M: Inlet Positive, Outlet Minus.
• WAGES follow WORK, not WORKERS: The hardest worker earns the most, regardless of how many workers there are.

• SBI Clerk Prelims usually has 1-2 Time and Work questions at easy to moderate level — aim to solve each in 45-60 seconds using LCM method.
• Pipes and Cisterns often appears as a disguised Time and Work question in Mains — do not panic, apply the same LCM approach.
• Watch for questions where a worker leaves before job completion — these test if you correctly calculate remaining work after departure.
• Wage distribution questions are more common in Mains than Prelims — they appear in Data Interpretation sets too, so know the ratio principle cold.
• If a question involves 3 or more workers with different start and stop times, draw a small timeline on rough paper — it prevents mixing up who worked on which days.