Time and Work PYQs for UPSC (2011-2024) | Solved Questions & PDF Download

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Year-Wise Time and Work PYQs (2011-2024)

Q1. In a garrison, there was food for 1000 soldiers for one month. After 10 days, 1000 more soldiers joined the garrison. How long would the soldiers be able to carry on with the remaining food? [CSAT 2013]

(a) 25 days

(b) 20 days

(c) 15 days

(d) 10 days

Solution:

Given that,

In a garrison, there was food for 1000 soldiers for one month.

After 10 days, 1000 more soldiers joined the garrison.

Now,

Let suppose 1 soldier eats 1 part of food

1000 solders eat = 1000 x 1 = 1000 part per day

For a month total amount of food = 30 x 1000 = 30000 part

For 10 days soldier eat = 10 x 1000 = 10000 part of food

Remaining amount left = 30000 - 10000 = 20000 part of food

Thereafter 1000 soldiers more are added

Total soldiers = 2000

Food required per day = 2000 x 1 = 2000 part per day

Total number of days food can sustain = 20000/2000 = 10 days

Hence option (d) is correct

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Q2. Ram and Shyam work on a job together for four days and complete 60% of it. Ram takes leave then and Shyam works for eight more days to complete the job. How long would Ram take to complete the entire job alone? [CSAT 2016]

(a) 6 days

(b) 8 days

(c) 10 days

(d) 11 days

Solution:

Given that,

Ram and Shyam work on a job together for four days and complete 60% of it.

Ram takes leave then and Shyam works for eight more days to complete the job.

Now,

Let the work be W

Efficiency of Ram and Shyam be E₁ and E₂

Days taken to Complete whole work = 4 x (10/6) = 20/3

Remaining work =  (E₁ + E₂) x 8/3 = E₂  x 8

E₁ = 2 x E₂

E₁ : E₂ = 2 : 1

Ram can complete whole work in = [3 x (20/3)/2] = 10 days

Hence option (c) is correct

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Q3. W can do 25% of a work in 30 days, X can do 1/4 of the work in 10 days, Y can do 40% of the work in 40 days and Z can do 1/3 of the work in 13 days. Who will complete the work first? [CSAT 2016]

(a) W

(c) Y

(b) X

(d) Z

Solution:

Given that,

W can do 25% of a work in 30 days

X can do 1/4 of the work in 10 days

Y can do 40% of the work in 40 days

Z can do 1/3 of the work in 13 days

Now,

Let the total work be a

W = 25% of a in 30 days

a/4 = 30 days

a = 120 days

X = a/4 of work in 10 days

a = 40 days

Y = 40% of a = 40 days

4a/10 = 40

a = 100 days

Z = 1/3 of a = 13 days

a = 39 days

Thus Z completes the work first

Hence option (d) is correct

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Q4. P works thrice as fast as Q, whereas P and Q together can work four times as fast as R. If P, Q and R together work on a job, in what ratio should they share the earnings? [CSAT 2017]

(a) 3:1:1

(b) 3:2:4

(c) 4:3:4

(d) 3:1:4

Solution:

Given that,

P works thrice as fast as Q, whereas P and Q together can work four times as fast as R.

P, Q and R together work on a job

Now,

P = 3Q....(i)

P + Q = 4R.....(ii)

Thus, Q = R.....(iii)

So, P = 3R

Therefore the ratio = P : Q : R = 3 : 1 : 1

Hence option (a) is correct

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Q5. A person X can complete 20% of work in 8 days and another person Y can complete 25% of the same work in 6 days. If they work together, in how many days will 40% of the work be completed?[CSAT 2020]

(a) 6

(c) 10

(b) 8

(d) 12

Solution:

Given that,

X can complete 20% of work in 8 days

Y can complete 25% of the same work in 6 days.

Now,

Let the total work be T

For X,

20% of T =  T/5

Per day work done = (T/5)/8 = T/40

For Y

25% of T = T/4

Per day work done = (T/4)/6 = T/24

Working together = T/40 + T/24 = T/15 per day

So, 40% work can be completed in = (4T/10)/(T/15) = 6 days

Hence option (a) is correct

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Q6. A man completes 7/8 of a job in 21 days. How many more days will it take him to finish the job if quantum of work is further increased by 50%? [CSAT 2021]

(a) 24

(b) 21

(c) 18

(d) 15

Solution:

Given that,

A man completes 7/8 of a job in 21 days.

Quantum of work is further increased by 50%

Now,

Time taken to complete the job = 21/7/8 = 24 days

Time to complete 50% of job = 24 x (50/100) = 12 days

Remaining work = 1 - 7/8 = 1/8

Time taken to complete 1/8 of work = 24 - 21 = 3

Number of days required = 12 + 3 = 15 days

Hence option (d) is correct

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Q7. 24 men and 12 women can do a piece of work in 30 days. In how many days can 12 men and 24 women do the same piece of work? [CSAT 2022]

(a) 30 days

(b) More than 30 days

(c) Less than 30 days or more than 30 days

(d) Data is inadequate to draw any conclusion

Solution:

Given that,

24 men and 12 women can do a piece of work in 30 days.

Now,

As there is no comparative analysis provided for men and women, thus time taken by 12 men and 24 women cannot be determined.

Hence option (d) is correct

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Q8. A, B, C working independently can do a piece of work in 8, 16 and 12 days respectively. A alone works on Monday, B alone works on Tuesday, C alone works on Wednesday; A alone, again works on Thursday and so on. Consider the following statements: [CSAT 2023]

1. The work will be finished on Thursday.

2. The work will be finished in 10 days.

Which of the above statements is/are correct?

(a) 1 only

(c) Both 1 and 2

(b) 2 only

(d) Neither 1 nor 2

Solution:

Given that,

A, B, C working independently can do a piece of work in 8, 16 and 12 days respectively.

A alone works on Monday

B alone works on Tuesday

C alone works on Wednesday

A alone, again works on Thursday and so on.

Now,

LCM of 8,16 and 12 = 48

Total amount of work = 48

Thus,

Efficiency of A = 48/8 = 6 unit per day

Efficiency of B = 48/16 = 3 unit per day

Efficiency of C = 48/12 = 4 unit per day

Work done in 3 days = 6 + 3 + 4 = 13 units

Therefore, the cycle repeats in 3 days

So, 48/13 = 3 cycles and 9 units of work will remain

3 cycles = 3  x 3 = 9 days

Thus on the 10th day (Wednesday) A will work 6 units of work and on next day (Thursday) B will complete the remaining work which is on Thursday

1. The work will be finished on Thursday.

The work will be finished on Thursday by B

Hence statement 1 is correct

2. The work will be finished in 10 days.

Hence statement 2 is incorrect

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Q9. A certain number of men can complete a piece of work in 6k days, where k is a natural number. By what percent should the number of men be increased so that the work can be completed in 5k days? [CSAT 2024]

(a) 10%

(b) (50/3)%

(c) 20%

(d) 25%

Solution:

Given that,

A piece of work that can be completed = 6k days, k is a natural number

Now,

Let number of men be M₁ and M₂

Days required to finish the work is D₁ and D₂

According to question the piece of work is same

So,

M₁ x D₁ = M₂ x D₂........(i)

As, D₁ = 6k days and D₂ = 5k days

M₁ x 6k = M₂ x 5k

(M₁ x 6k)/5k = M₂......(ii)

% change from M₁ to M₂ = {[(M₁ x 6k)/5k]/ M₁} x 100 = 120%

Thus % increase of men of M₂ = 120 - 100 = 20 % more men are required to finish the task in 5k days

Hence option (c) is correct

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10. X, Y and Z can complete a piece of work individually in 6 hours, 8 hours and 8 hours respectively. However, only one person at a time can work in each hour and nobody can work for two consecutive hours. All are engaged to finish the work. What is the minimum amount of time that they will take to finish the work? [CSAT 2024]

(a) 6 hours 15 minutes

(b) 6 hours 30 minutes

(c) 6 hours 45 minutes

(d) 7 hours

Solution:

Given that,

X, Y, Z can complete a piece of work in 6hr, 8hr, 8hr

No one works for two consecutive hours and only one person at a time can work in each hour

Now,

LCM of 6, 8 and 8 = 24

Total work unit = 24 units

So, X can complete a unit of work in an hour = 24/6 = 4 units/hr

Y can complete a unit of work in an hour = 24/8 = 3 units/hr

Z can complete a unit of work in an hour = 24/8 = 3 units/hr

Hours	Unit of work
1st hour	X = 4 units
2nd hour	Y/Z = 3 units
3rd hour	X =  4 units
4th hour	Y/Z = 3 units
5th hour	X = 4 units
6th hour	Y/Z = 3 units

Total work in 6 hours = 4 + 3 + 4 + 3 + 4 + 3 = 21units

Total work to complete = 24 units

Remaining work = 24 - 21 = 3 units

7th hour X will work

X work per min = 4/60 = 1/15 = 1 unit of work per 15 minutes

So, total time for 3 units = 45 min

X will complete remaining 3 units in 45 minutes

Total time taken = 6 hours 45 min

Hence option (c) is correct

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ANSWER KEY

1. 1.      D
2. 2.      C
3. 3.      D
4. 4.      A
5. 5.      A
6. 6.      D
7. 7.      D
8. 8.      A
9. 9.      C
10. 10.  C

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Download Time and Work PYQs PDF

• ➡️ Download the complete set of Time and Work PYQs (2011-2024) with solutions in PDF format.
• ➡️ Click Here to Download PDF

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FAQs on Time and Work for UPSC

1. How important is Time and Work for UPSC CSAT?

➡️ Extremely important - typically 2-3 questions appear every year in CSAT Paper II.

2. What's the best approach to solve Time and Work problems?

• ➡️ Convert all work to work/day rates
• ➡️ Use LCM method for complex problems
• ➡️ Practice worker addition/removal scenarios

3. Any shortcut formulas to remember?

➡️ If A’s rate=1x,B’s rate=1yCombined time=xyx+yIf A’s rate=x1​,B’s rate=y1​Combined time=x+yxy​

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Conclusion

Mastering Time and Work PYQs gives you an edge in UPSC CSAT. This page provides:
✅ Year-wise solved questions (2011-2024)
✅ PDF download of all PYQs
✅ Efficiency-boosting strategies

For more UPSC resources, visit iassetu.com.

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