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An employee starts work on 1 January 2000 on an annual salary of $30,000.
His pay scale will give him an increase of $800 per annum
on the first of January until 1 January 2015 inclusive.
He remains on this salary until he retires on 31st December 2040.
How much will he earn during his working life.
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His annual salaries from 01/01/2000 to 12/31/2015 form an arithmetic progression
with the first term = 30000 dollars and common difference d= 800 dollars.
In particular, his annual salary for the year 2015 is
= 30000 + 15*800 = 42000 dollars (the 16-th term of the AP).
Thus, from 01/01/2000 till 12/31/2015 he earned = 576000 dollars.
From 01/01/2016 to 12/31/2040, his annual earning rate was constant 42000 dollars per year
during (40-15) = 25 years.
So, during these 25 years, he earns 25*42000 = 1050000 dollars.
The total earning during his working life will be this sum
576000 + 1050000 = 1,626,000 dollars. ANSWER
Solved.
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For introductory lessons on arithmetic progressions see
- Arithmetic progressions
- The proofs of the formulas for arithmetic progressions
- Problems on arithmetic progressions
- Word problems on arithmetic progressions
in this site.