math help plz!
posted by Amy on .
DigiCom wants to drop the effective rate of interest on its credit card by 2%. If it currently charges a nominal rate of 8% compounded daily, at what value should it set the new nominal rate? Note: Please make sure your final answer(s) are in percentage form and are accurate to 2 decimal places. For example 34.56%
The correct answer was: 6.14%
You should first calculate the effective rate with the formula:
f = (1 + i)m  1
where f is the effective rate, i is the periodic rate, and m is the number of compoundings per year.
You shoud obtain 0.08%. Then you should change that rate and convert back by rearranging the formula.
i need help understanding how to get that same answer!

nvm...i got this...

m is 365 days in a year
I think you mean:
f = (1 + i)^m  1 So to the power m
where i = nominal rate/365
i = .08/365
so
f = (1 +.08/365)^365 = 1.0833
so 8.33% is present effective rate
Now
we want to go down 2%
so
6.33 % is new effective rate
so
1.0633 = (1 + r/365)^365
log 1.0633 = 365 log (1 + r/365)
.00007302963 = log (1+ r/365)
1+r/365 = 1.000168171
r =.0614
or
6.14% 
THNX again!!! :D