Math Problem Statement

3 men and 7 women can complete a work in 10 days. But 4 men and 6 women need 8 days to complete the same work. In how many days will 10 women complete the same work?

Solution

Let's assign variables to the daily work rates of men and women:

  • Let the work rate of a man be mm (fraction of the work completed by one man in one day).
  • Let the work rate of a woman be ww (fraction of the work completed by one woman in one day).

Step 1: Formulate two equations based on the problem's data.

  • First condition: 3 men and 7 women complete the work in 10 days.

    In one day, the combined work done by 3 men and 7 women is 3m+7w3m + 7w. Since they complete the entire work in 10 days, the daily work rate must be 110\frac{1}{10}: 3m+7w=1103m + 7w = \frac{1}{10}

  • Second condition: 4 men and 6 women complete the work in 8 days.

    Similarly, in one day, the combined work done by 4 men and 6 women is 4m+6w4m + 6w. Since they complete the entire work in 8 days, the daily work rate must be 18\frac{1}{8}: 4m+6w=184m + 6w = \frac{1}{8}

Step 2: Solve the system of equations.

We now have the system: 3m + 7w = \frac{1}{10} \tag{1} 4m + 6w = \frac{1}{8} \tag{2}

We can solve this system by elimination or substitution. Let's first multiply equation (1) by 4 and equation (2) by 3 to align the coefficients of mm:

12m + 28w = \frac{4}{10} = 0.4 \tag{3} 12m + 18w = \frac{3}{8} = 0.375 \tag{4}

Now subtract equation (4) from equation (3):

(12m+28w)(12m+18w)=0.40.375(12m + 28w) - (12m + 18w) = 0.4 - 0.375 10w=0.02510w = 0.025 w=0.02510=0.0025w = \frac{0.025}{10} = 0.0025

Step 3: Substitute w=0.0025w = 0.0025 into one of the original equations to find mm.

Substitute w=0.0025w = 0.0025 into equation (1): 3m+7(0.0025)=1103m + 7(0.0025) = \frac{1}{10} 3m+0.0175=0.13m + 0.0175 = 0.1 3m=0.10.0175=0.08253m = 0.1 - 0.0175 = 0.0825 m=0.08253=0.0275m = \frac{0.0825}{3} = 0.0275

Step 4: Find how long it takes for 10 women to complete the work.

The work done by 10 women in one day is 10w10w. Since w=0.0025w = 0.0025, the combined daily work rate of 10 women is: 10w=10×0.0025=0.02510w = 10 \times 0.0025 = 0.025

Thus, the number of days it will take for 10 women to complete the work is: Number of days=10.025=40\text{Number of days} = \frac{1}{0.025} = 40

Final Answer:

It will take 40 days for 10 women to complete the work.


Would you like more details or have any questions?

Here are 5 related questions for further practice:

  1. How many days will 5 men take to complete the same work alone?
  2. If 6 men and 4 women work together, how long will they take to complete the work?
  3. What is the total work rate of 2 men and 8 women together?
  4. How many men are needed to complete the work in 6 days if no women are involved?
  5. What if 1 man and 10 women work together—how long will it take them to complete the work?

Tip: When dealing with work problems, always convert rates into fractions of the total work per day to solve efficiently.

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Math Problem Analysis

Mathematical Concepts

Algebra
Work and Time
Linear Equations

Formulas

Work rate of men and women: Work = Rate × Time
System of linear equations: 3m + 7w = 1/10 and 4m + 6w = 1/8

Theorems

Solving systems of linear equations by elimination

Suitable Grade Level

Grades 9-12