Calculation of Average Salary

To solve this problem, we need to first understand how to calculate the average salary of a group of workers. The formula for calculating the average salary is:

Average Salary = Total Salary / Number of Workers

Given that the average salary of unskilled workers is 10000 and the average salary of skilled workers is 15000, we can set up the following equations:

Total Salary of Unskilled Workers / Number of Unskilled Workers = 10000
Total Salary of Skilled Workers / Number of Skilled Workers = 15000

Combining Salaries

We are also given that the combined salary of both groups is 12000. We can use this information to set up another equation:

Total Salary of Unskilled Workers + Total Salary of Skilled Workers = 12000

Solving for Number of Skilled Workers

We can now use these equations to solve for the number of skilled workers. First, we can rearrange the equation for the average salary of unskilled workers to solve for the total salary of unskilled workers:

Total Salary of Unskilled Workers = 10000 * Number of Unskilled Workers

We can do the same for skilled workers:

Total Salary of Skilled Workers = 15000 * Number of Skilled Workers

Substituting these equations into the equation for the combined salary, we get:

10000 * Number of Unskilled Workers + 15000 * Number of Skilled Workers = 12000

Simplifying this equation, we get:

2 * Number of Unskilled Workers + 3 * Number of Skilled Workers = 4 * Number of Workers

We know that the total number of workers is the sum of the number of unskilled and skilled workers, so we can substitute this into the equation:

2 * Number of Unskilled Workers + 3 * Number of Skilled Workers = 4 * (Number of Unskilled Workers + Number of Skilled Workers)

Simplifying this equation, we get:

Number of Skilled Workers = 2 * Number of Unskilled Workers

We can now use this equation to solve for the percentage of skilled workers:

Percentage of Skilled Workers = Number of Skilled Workers / (Number of Unskilled Workers + Number of Skilled Workers) * 100%

Substituting in the equation we just found, we get:

Percentage of Skilled Workers = 2 * Number of Unskilled Workers / (3 * Number of Unskilled Workers) * 100%

Simplifying this equation, we get:

Percentage of Skilled Workers = 2/3 * 100%

Percentage of Skilled Workers = 66.67%

Therefore, the percentage of unskilled workers is 100% - 66.67% = 33.33%.

However, the answer given in the question is 40%. This means there may be an error in the problem or in the answer provided.