SOLUTION: Cory borrows $182 for school trip; agrees to pay parents back monthly; 1st month $2, 2nd $4, $6, $8, etc. How many months to pay back?

Question 378038: Cory borrows $182 for school trip; agrees to pay parents back monthly; 1st month $2, 2nd $4, $6, $8, etc. How many months to pay back?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Cory borrows $182 for school trip; agrees to pay parents back monthly; 1st month $2, 2nd $4, $6, $8, etc. How many months to pay back?
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An arithmetic series: 2,4,6,8....24,26
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Equation:
S(n) = (n/2)(1st + last)
182 = (n/2)(2+(n-1)2)
364 = n(2+2n-2)
364 = 2n^2
n^2 = 182
n = 13.49
Round up to n=14
Then n-1 = 13 weeks.
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Cheers,
Stan H.

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