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Question

Three workers, X, Y, and Z, can complete a certain job in 10 days, 12 days, and 15 days, respectively. Determine the number of days required for them to complete the job when they work together.

This question was previously asked in
RRB ALP 2025 CBT 2 Wiremen Question Paper (28-Jul-2026) (Shift 2)
The correct answer is

4 days

To determine the number of days required for workers X, Y, and Z to complete the job together, we use the concept of work and time, specifically the formula for combined work rate.

Step 1: Determine the work rate of each worker.

  • Worker X can complete the job in 10 days, so X's work rate is \(\frac{1}{10}\) of the job per day.
  • Worker Y can complete the job in 12 days, so Y's work rate is \(\frac{1}{12}\) of the job per day.
  • Worker Z can complete the job in 15 days, so Z's work rate is \(\frac{1}{15}\) of the job per day.

Step 2: Calculate the combined work rate.

The combined work rate when all workers work together is the sum of their individual work rates:

\(\frac{1}{10} + \frac{1}{12} + \frac{1}{15}\)

To add these fractions, we need a common denominator. The least common multiple of 10, 12, and 15 is 60.

Convert each work rate to have a denominator of 60:

  • \(\frac{1}{10} = \frac{6}{60}\)
  • \(\frac{1}{12} = \frac{5}{60}\)
  • \(\frac{1}{15} = \frac{4}{60}\)

Add these together:

\(\frac{6}{60} + \frac{5}{60} + \frac{4}{60} = \frac{15}{60} = \frac{1}{4}\)

Step 3: Calculate the time to complete the job together.

Since their combined work rate is \(\frac{1}{4}\), they can complete \(\frac{1}{4}\) of the job in one day. Therefore, they will complete 1 whole job in:

\(4 \text{ days}\)

Thus, the correct answer is 4 days.

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Similar Questions

  1. P is 30% more efficient than Q. How much time will they, working together, take to complete a job that P alone could have done in 23 days?

  2. 8 men and 12 women can build a wall in 10 days. 6 men and 8 women can build the same wall in 14 days. How long will it take for 2 women and 1 man to build it together?

  3. If 6 men and 8 boys can do a piece of work in 10 days, while 26 men and 48 boys can do the same work in 2 days, then the time taken by 10 men and 20 boys for doing the same piece of work will be:

  4. 8 men and 12 women can build a wall in 10 days. 6 men and 8 women can build the same wall in 14 days. How long will it take for 1 woman to build it alone?

  5. Ravi and Kumar are working on an assignment. Ravi takes 6 hours to type 32 pages on a computer, while Kumar takes 5 hours to type 40 pages. How much time will they take, working together on two different computers to type an assignment of 110 pages?

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  9. A can complete a piece of work in 20 days and B can do the same work in 15 days. B worked alone for 6 days and left. In how many days can A complete the remaining work alone?

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Important Questions from Time and work

  1. A person 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?

  2. 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?

  3. There are three pillars X, Y and Z of different heights. Three spiders A, B and C start to climb on these pillars simultaneously. In one chance, A climbs on X by 6 cm but slips down 1 cm. B climbs on Y by 7 cm but slips down 3 cm. C climbs on Z by 6.5 cm but slips down 2 cm. If each of them requires 40 chances to reach the top of the pillars, what is the height of the shortest pillar?

  4. There is an order of 19000 quantity of a particular product from a customer. The firm produces 1000 quantity of that product per out of which 5% are unfit for sale. In how many days will the order be completed?

  5. 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?

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