Acredit card had an apr of 15.21 all of last year and compounded interest daily. what was the credit cards effective interest rate last year? a) 11.64% b) 15.21 c) 16.42% d) 16.32%

Let P =  the principal
The apr is r = 15.21% = 0.1521
The compounding interval is n = 365
The time is t = 1 year

The value after 1 year is

That is,
A = P(1 + 0.1521/365)³⁶⁵ = 1.1642P
The interest is 1.1642P - P = 0.1642P

The effective percent interest rate is
100(0.1642P/P) = 16.42%

16.42%

Yes i believe the answer is b. it seems to be the most logical answer. hope this . : )