SOLUTION: If money is invested for 4 years at a simple interest rate of 13.2% per annum, the nominal interest rate per annum, compounding monthly, is (as a percentage rounded to three decima

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Question 1146563: If money is invested for 4 years at a simple interest rate of 13.2% per annum, the nominal interest rate per annum, compounding monthly, is (as a percentage rounded to three decimal places; no % sign):
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Since the principal invested is not given, let
+P+=+1000+
+r+=+.132+
For simple interest:
+I+=+P%2Ar%2At+
+I+=+1000%2A.132%2A4+
+I+=+1000%2A.528+
+I+=+528+
--------------------------
If this were a compounded interest received,
+A+=+P%2A%28+1+%2B+r%2Ft+%29%5E%28n%2At%29+
+A+=+P+%2B+I+
+A+=+1528+
+P+=+1000+
+t+=+4+
+n+=+12+
--------------------
+1528+=+1000%2A%28+1+%2B+r%2F4+%29%5E%2812%2A4%29+
+1.528+=+%28+1+%2B+r%2F4+%29%5E48+
Take the log base 10 of both sides
+log%28+1.528+%29+=+48%2Alog%28%28+1+%2B+r%2F4+%29%29+
+.184123+=+48%2Alog%28%28+1+%2B+r%2F4+%29%29+
+log%28%28+1+%2B+r%2F4+%29%29+=+.003836+
+1+%2B+r%2F4+=+10%5E.003836+
+1+%2B+r%2F4+=+1.0088718+
+r%2F4+=+.0088718+
+r+=+.03549+
Rounded off:
+r+=+.035+
---------------------
check:
+log%28%28+1+%2B+r%2F4+%29%29+=+.003836+
+log%28%28+1+%2B+.0088718+%29%29+=+.003836+
+10%5E.003836+=+1.0088718+
This checks on my calculator
Get 2nd opinion if needed