# 11.5.2. Series and Summation Notation

The sum of the monthly salaries of an employee at the end of a year is LE. Given that the sum increases by a rate of every year, use the summation notation to describe the sum of his salaries after 5 years of work, then determine this sum to the nearest two decimal places.

• ALE
• BLE
• CLE
• DLE

### Example

The sum of the monthly salaries of an employee at the end of a year is LE. Given that the sum increases by a rate of every year, use the summation notation to describe the sum of his salaries after 5 years of work, then determine this sum to the nearest two decimal places.

### Solution

Initially, the salary of the employee was (i.e., ). Each year, he receives an pay rise. We can express this mathematically as follows: . Consequently,

Hence, the express for his salary in the year is . Therefore, his total income over the first 5 years can been expressed as

To calculate this value we can use the multiplication property of summation notation.

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