SOLUTION: A principal of $5600.00 was deposited for 3years at compound interest. If the interest earned was $1200.00,find the interest rate per annum THANK YOU

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Question 1046800: A principal of $5600.00 was deposited for 3years at compound interest. If the interest earned was $1200.00,find the interest rate per annum
THANK YOU
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
+A+=+P%2A%28+1+%2B+r%2Fn+%29%5E%28n%2At%29+
Let +I+ = the interest earned
given:
+P+=+5600+
+t+=+3+
+I+=+1200+
+n+=+1+ ( I'm assuming this )
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The interest earned, +I+ is:
+I+=+P%2A%28+1+%2B+r%2Fn+%29%5E%28n%2At%29+-+P+
+1200+=+5600%2A%28+1+%2B+r%2F1+%29%5E%28+1%2A3+%29+-+5600+
+1200+=+5600%2A%28+1+%2B+r+%29%5E3+-+5600+
+1200%2F5600+=+%28+1+%2B+r+%29%5E3+-+1+
+3%2F14+=+%28+1+%2B+r+%29%5E3+-+1+
+17%2F14+=+%28+1+%2B+r+%29%5E3+
Take the log base 10 of both sides
+log%28+17+%29+-+log%28+14+%29+=+3%2Alog%28%28+1+%2B+r+%29%29+
+1.23045+-+1.14613+=+3%2Alog%28%28+1+%2B+r+%29%29+
+3%2Alog%28%28+1+%2B+r+%29%29+=+.084322+
+log%28%28+1+%2B+r+%29%29+=+.028107+
+1+%2B+r+=+10%5E.028107+
+1+%2B+r+=+1.06686+
+r+=+.06686+
the annual interest rate is 6.69%
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check my math & get a 2nd opinion