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Question

The efficiency of A, B and C is 2 : 3 : 5. A alone can complete the work in 40 days. They all worked together for 5 days and then C left the work. In how many days can A and B together complete 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

6 days

Efficiency Ratio Interpretation

The efficiency ratio of A, B, and C is given as $2:3:5$. This implies that their rates of work are in this proportion.

Let the amount of work done per day by A, B, and C be $2x$, $3x$, and $5x$ units respectively. Here, $x$ represents a common factor.

Calculating Total Work

We know that A alone can complete the work in 40 days.

  • Work done by A per day = $2x$ units.
  • Total work = (Work rate of A) $\times$ (Time taken by A)
  • Total work = $2x \times 40 = 80x$ units.

Work Done Together

A, B, and C worked together for 5 days.

  • Combined work rate of A, B, and C = $2x + 3x + 5x = 10x$ units per day.
  • Work done in 5 days = (Combined work rate) $\times$ (Time)
  • Work done in 5 days = $10x \times 5 = 50x$ units.

Calculating Remaining Work

After 5 days, the remaining work is calculated as:

  • Remaining Work = Total Work - Work done in 5 days
  • Remaining Work = $80x - 50x = 30x$ units.

Time for A and B to Complete Remaining Work

C left the work, and A and B together completed the remaining work.

  • Combined work rate of A and B = $2x + 3x = 5x$ units per day.
  • Number of days required = $\frac{\text{Remaining Work}}{\text{Combined work rate of A and B}}$
  • Number of days required = $\frac{30x}{5x} = 6$ days.
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Similar Questions

  1. A can complete a task in $30\text{ days}$, and B can complete the same task in $40\text{ days}$. They work together for $10\text{ days}$, and then C joins them and completes the remaining work in $5\text{ days}$. How long will C alone take to complete the task?
  2. A and B can complete a task in 12 days together. A is 25% more efficient than B. What percentage of the work is done by A alone?

  3. 20 women can do work in 16 days. 10 men can complete the same work in 12 days. What is the ratio between the efficiency of a man and a woman?

  4. Sameer can complete a work in 16 days. In how many days will the work be completed by Ajay, if his efficiency is 60% more than that of Sameer?

Important Questions from Work Efficiency

  1. 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 further increased by 50%?

  2. 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?

  3. A and B together can do a piece of work in 4 days, B and C can do it in 6 days, A and C can do it in 8 days. Then A, B and C together can do the same work in :-

  4. A can complete 50% of a work in 9 days and B can do 25% of the work in 9 days, if they work alone. If they work together then how much work (in percentage) can be completed in 6 days?

  5. A is thrice as good a workman as B. C alone takes 48 days to paint a house. All three A, B and C working together take 16 days to paint the house. It will take how many days for A alone to paint the house?

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