To compute the arithmetic mean of the salaries from the given distribution, we need to follow these steps:

Step 1: Identify the midpoints (class marks) of each salary class

The midpoint for each class interval is calculated by taking the average of the lower and upper boundaries of each class.

$\text{Midpoint} = \frac{\text{Lower limit} + \text{Upper limit}}{2}$

Here are the class intervals and their midpoints:

• $0 - 500$: Midpoint = $\frac{0 + 500}{2} = 250$
• $500 - 1000$: Midpoint = $\frac{500 + 1000}{2} = 750$
• $1000 - 1500$: Midpoint = $\frac{1000 + 1500}{2} = 1250$
• $1500 - 2000$: Midpoint = $\frac{1500 + 2000}{2} = 1750$
• $2000 - 2500$: Midpoint = $\frac{2000 + 2500}{2} = 2250$
• $2500 - 3000$: Midpoint = $\frac{2500 + 3000}{2} = 2750$
• $3000 - 3500$: Midpoint = $\frac{3000 + 3500}{2} = 3250$
• $3500 - 4000$: Midpoint = $\frac{3500 + 4000}{2} = 3750$
• $4000 - 4500$: Midpoint = $\frac{4000 + 4500}{2} = 4250$

Step 2: Multiply the midpoints by the number of employees

Now we multiply each midpoint by the corresponding number of employees in that salary range:

$\text{Mean contribution} = \text{Midpoint} \times \text{No. of employees}$