A man can finish a work in 12 days and a woman can finish the same work in 10 days. 2 men and 3 women work on alternate days and men start the first day. In how many days, the work will be finished?

Let the total work be represented as \( W \) (a whole unit).

1. **Work done by one man in one day**:
   A man can finish the work in 12 days, so the work done by one man in one day is:
   \[
   \text{Work done by 1 man in 1 day} = \frac{1}{12}
   \]

2. **Work done by one woman in one day**:
   A woman can finish the work in 10 days, so the work done by one woman in one day is:
   \[
   \text{Work done by 1 woman in 1 day} = \frac{1}{10}
   \]

3. **Work done by 2 men in one day**:
   Since 2 men are working on alternate days, the work done by 2 men in one day is:
   \[
   \text{Work done by 2 men in 1 day} = 2 \times \frac{1}{12} = \frac{2}{12} = \frac{1}{6}
   \]

4. **Work done by 3 women in one day**:
   The work done by 3 women in one day is:
   \[
   \text{Work done by 3 women in 1 day} = 3 \times \frac{1}{10} = \frac{3}{10}
   \]

5. **Work done in two consecutive days**:
   Men and women work on alternate days, with men starting on the first day. So, the total work done in two consecutive days (one day of men and one day of women) is:
   \[
   \text{Work done in 2 days} = \frac{1}{6} + \frac{3}{10}
   \]

   To sum these fractions, we find a common denominator:
   \[
   \frac{1}{6} + \frac{3}{10} = \frac{5}{30} + \frac{9}{30} = \frac{14}{30} = \frac{7}{15}
   \]
   Therefore, the work done in two consecutive days is \( \frac{7}{15} \) of the total work.

6. **Number of such 2-day cycles**:
   To finish the entire work \( W = 1 \), let’s find how many full 2-day cycles are needed. The total work done in \( n \) such cycles is:
   \[
   \text{Total work in } n \text{ cycles} = n \times \frac{7}{15}
   \]
   Setting this equal to 1 to find \( n \):
   \[
   n \times \frac{7}{15} = 1
   \]
   Solving for \( n \):
   \[
   n = \frac{15}{7}
   \]
   This means approximately \( 2.14 \) full cycles are needed. Each cycle consists of 2 days, so in 2 full cycles (4 days), \( \frac{14}{15} \) of the work will be completed.

7. **Remaining work after 4 days**:
   After 4 days (2 full cycles), the work done is:
   \[
   \text{Work done in 4 days} = 2 \times \frac{7}{15} = \frac{14}{15}
   \]
   So, the remaining work is:
   \[
   1 - \frac{14}{15} = \frac{1}{15}
   \]

8. **Final day (worked by men)**:
   On the 5th day, 2 men work. The work they complete in 1 day is:
   \[
   \frac{1}{6}
   \]
   Since \( \frac{1}{6} > \frac{1}{15} \), the men will complete the remaining work in less than a full day.

9. **Time taken on the 5th day**:
   To calculate the fraction of the day required to finish the remaining \( \frac{1}{15} \) of the work:
   \[
   \text{Fraction of day required} = \frac{\frac{1}{15}}{\frac{1}{6}} = \frac{1}{15} \times \frac{6}{1} = \frac{6}{15} = \frac{2}{5}
   \]
   So, the men will finish the work in \( \frac{2}{5} \) of the 5th day.

Thus, the total number of days to complete the work is:
\[
4 \text{ full days} + \frac{2}{5} \text{ of the 5th day} = 4 + 0.4 = 4.4 \text{ days}
\]

Therefore, the work will be finished in **4.4 days**.

---

Would you like more details or have any questions? Here are 5 related questions to explore:

1. How would the answer change if the woman started on the first day instead?
2. What if the number of men and women working was swapped (3 men, 2 women)?
3. How would you calculate the work completed if only one man and one woman worked alternately?
4. Can you find a formula to generalize this problem for different work rates?
5. How can you use the concept of work rates to solve problems involving machines?

**Tip:** When dealing with alternating workers, always calculate the work completed in one cycle before extending it to the total work.

Solve the work and time problem where 2 men and 3 women work on alternate days to complete a task. Learn key concepts like work rates, unit fractions, and the formula to determine the time required to finish the work. Suitable for Grades 9-10 students.

Math Problem Statement

Solution

Ask a new question for Free

By Image

Math Problem Analysis

Mathematical Concepts

Formulas

Theorems

Suitable Grade Level

Related Recommendation