Question 1081527: when Lisa was born, her parents decided to put $250 times her age away for her at every birthday through her 18th birthday. This money will help Lisa go to college. How much money will they have saved after her 18th birthday (do not take into account any interest earned)?
Answer by chen(11)   (Show Source):
You can put this solution on YOUR website! When she was born, we assume they put away 0*250=$0
After her 1st birthday, 1*250
After her 2nd birthday, 2*250
...
After her 18th birthday, 18*250.
So the total amount will be (1+2+...+18)*250.
The parenthesis is an arithmetic series with constant term 1, so it equals:
(18*19/2)*250 = $42,750.
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