Question 1085929: A man's salary started with $7,500 for the first year and increase by $750 each year up to a maximum of $15,000 per annum at which it remains constant. Find his total earning in his thirty years of service.
Found 2 solutions by Boreal, MathTherapy:
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! 1-7500
2-8250
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11-15000
12-30-15000
The last 19 years was 19*$15,000=$285,000
The sum of the first is 11*the average $11,250 or $123,750
The total is $408,750.
Answer by MathTherapy(10551)  (Show Source):
You can put this solution on YOUR website!
A man's salary started with $7,500 for the first year and increase by $750 each year up to a maximum of $15,000 per annum at which it remains constant. Find his total earning in his thirty years of service.
Ask yourself, "How long after starting will it take him to make the maximum of $15,000?
With T being time (in years), we get: T * 750 + 7,500 = 15,000 =======> 750T = 15,000 - 7,500 =====> 750T = 7,500 ======> 
Now, use the formula for the sum of an AP:  to get the amount earned 10 years after starting. This should give you: $108,750
From years 11 - 30 (20 year span), he would've earned 20(15,000), or $300,000.
Adding the 1st 10 years' earnings to the last 20 years' earnings, we get: 
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