SOLUTION: Pablo deposited $57 into a savings account for which interest is compounded quarterly. According to the rule of 72, what interest rate will cause his money to double in approximate

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Question 869871: Pablo deposited $57 into a savings account for which interest is compounded quarterly. According to the rule of 72, what interest rate will cause his money to double in approximately 44 years?
Answer by LinnW(1048) About Me  (Show Source):
You can put this solution on YOUR website!
set r = annual rate
72%2F%28%281%2F4%29%2Ar%29+=+44%2A4
44*4 is the number of compounding periods
72%2A4%2F%28r%29+=+176
288%2F%28r%29+=+176
so 176r = 288
r = 288/176
r = 1.636 percent or 0.01636
Let's check
1.01636^44 = just over 2