# Math Help - Help with finance calculator

1. ## Help with finance calculator

Poor Dog, Inc. borrowed $135,000 from the bank today. They must repay this money over the next six years by making monthly payments of$2,215.10. What is the interest rate on the loan? Express your answer with annual compounding.

Here is what I put in
n = 72
I% = 0
PV = -135000
PMT = 2215.1
FV = 0
p/y = 12
c/y = 12

and the answer I get is 5.65% which is wrong, the correct answer is 5.80% and I have no idea how to get it.

2. ## Re: Help with finance calculator

Originally Posted by nafiro
Poor Dog, Inc. borrowed $135,000 from the bank today. They must repay this money over the next six years by making monthly payments of$2,215.10. What is the interest rate on the loan? Express your answer with annual compounding.

Here is what I put in
n = 72
I% = 0
PV = -135000
PMT = 2215.1
FV = 0
p/y = 12
c/y = 12

and the answer I get is 5.65% which is wrong, the correct answer is 5.80% and I have no idea how to get it.
The periodic monthly rate comes out to 0.47%

It seems the reply you are getting is an annual rate and the reply in the book is an annualized rate

Annual Rate = 0.0047 * 12 = 0.0564 = 5.64%
Annualized Rate = (1+ 0.0047 )^12 - 1 = (1.0047 )^12 - 1 = 1.057881 - 1 = 0.057881 = 5.788%

Not sure how it would be implemented in your calculator though

I used this online Excel RATE calculator to find the monthly rate

3. ## Re: Help with finance calculator

You need to go an extra step, to calculate what 5.65% annual
compounded monthly represents as effective annual rate:
(1 + .0565/12)^12 - 1 = .0579832.... or 5.80% rounded.

Easier to see using PV:FV; say \$1000 earning 12% annual compounded monthly over 1 year:
1000(1 + .12/12)^12 = 1000(1.01)^12 = 1126.825...
You can "see" from that resulting balance that effective rate is 12.6825%