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Question

A contractor employs 15 men to complete a work in 24 days, working 8 hours per day. After six days, he adds five more men but also reduces the working hours to six per day from the seventh day onwards. If all men work with the same efficiency throughout, how many more days will be required to finish the remaining work?

This question was previously asked in
SSC CGL 2025 Tier 2 Paper 1 Question Paper (19-Jan-2026)
The correct answer is
18

This problem involves calculating the time required to complete the remaining work after changes in the number of workers and working hours.

Calculate Total Work Required

The total amount of work can be measured in 'man-hours'. Initially, the plan was:

  • Number of men: 15
  • Number of days: 24
  • Hours per day: 8

Total work = Number of men $\times$ Number of days $\times$ Hours per day

Total work = $15 \times 24 \times 8 = 2880$ man-hours.

Calculate Work Done in Initial Phase

The work was carried out for 6 days with the initial setup:

  • Number of men: 15
  • Number of days worked: 6
  • Hours per day: 8

Work done = $15 \times 6 \times 8 = 720$ man-hours.

Calculate Remaining Work

Subtract the work already done from the total work required:

Remaining work = Total work - Work done

Remaining work = $2880 - 720 = 2160$ man-hours.

Calculate New Work Rate and Time Needed

After 6 days, the conditions changed:

  • New number of men = 15 + 5 = 20
  • New hours per day = 6

Let the number of additional days required be $D$. The remaining work must be completed by the new workforce under the new conditions.

Remaining work = New number of men $\times$ Additional days ($D$) $\times$ New hours per day

$2160 = 20 \times D \times 6$

$2160 = 120 \times D$

$D = \frac{2160}{120}$

$D = 18$ days.

Therefore, 18 more days will be required to finish the remaining work.

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Similar Questions

  1. A and B can complete a task together in 12 days, while B and C can finish it in 16 days. After A works on it for 5 days and B for 7 days, C takes the remaining 13 days to finish the work. How many days would it take for C to complete the work alone?

  2. A is three times more efficient as a worker than B, which allows A to complete a job in 60 days less than B. If they work together, they can finish the job in:

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Important Questions from Time and Work

  1. Mohan can do a piece of work in 10 days and Sohan in 15 days. They started working together, but after 3 days Mohan left the work . What time will Sohan take to finish the work?

  2. A tank is filled in 8 hours by three taps A, B and C. The tap C is thrice as fast as B and B is twice as fast as A. How much time will pipe B alone take to fill the tank?

  3. Had been one menless, then the number of days required to do a piece of work would have been one more. If the number of Man. Days required to complete the work is 56, how many workers were there?

  4. A can do a piece of work in 16 hours, B and C can do it in 8 hours while A and C can do it 12 hours. How long will B alone take to do it?

  5. lf 12 men can do a work in 20 days, in how many days will the work be done by 15 men-
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