SOLUTION: Heather is collecting dimes. She saves 2 dimes the 1st day, 4 dimes the 2nd day and 6 dimes the 3rd day. If this pattern continues, how much money will she have at the end of 30 da

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Question 1006902: Heather is collecting dimes. She saves 2 dimes the 1st day, 4 dimes the 2nd day and 6 dimes the 3rd day. If this pattern continues, how much money will she have at the end of 30 days?
* please include the algebraic form, so I conceptually understand the problem. Thanks!
Answer by CubeyThePenguin(3113) About Me  (Show Source):
You can put this solution on YOUR website!
On the nth day, Heather saves 2n dimes. In n days, she has a total of:

2 + 4 + ... + 2n
= 2(1 + 2 + ... + n)
= 2+%2A+%28%28n%29%28n%2B1%29%29%2F2
= n(n+1) dimes.

We want to know how much money she has at the end of 30 days, so use n = 30.

# of dimes = 30(31) = 930
amount of money = $9.30