If in the sales department of a company, the average salary per employee is Rs. 350, average salary of 10 senior employees is Rs.450 per employee and average salary of remaining staff is Rs. 250 per employee, then what is the total number of employees working in the sales department?

Given:

The average salary per employee in the sales department is Rs. 350.

The average salary of 10 senior employees is Rs. 450 per employee.

The average salary of the remaining staff is Rs. 250 per employee.

Formula:

Average = (Sum of observations)/(Number of observations)

The sum of observations = Average × Number of observations

Calculation:

Let the total number of employees in the sales department be x.

The sum of salaries of all the employees in the sales department is:

(10 × 450) + (x - 10) × 250

The average salary per employee is given as Rs. 350, so we can write:

350 = [(10 × 450) + (x - 10) × 250]/x

Multiplying both sides by x, we get:

350x = (10 × 450) + (x - 10) × 250

Expanding the right-hand side, we get:

350x = 4500 + 250x - 2500

Simplifying and solving for x, we get:

100x = 2000

x = 20

Therefore, the total number of employees working in the sales department is 20.