Respuesta :
Option c is correct, 0.1689.
Effective Interest rate
We know, the formula for effective interest rate,
[tex]r = (1 + \dfrac{i}{n} )^n - 1[/tex],
where,
r = effective interest rate,
i = stated interest rate,
n = number of compounding periods,
Given to us,
Stated interest rate = 8.145%,
Tiffany's effective interest rate
Tiffany's effective interest rate be if the interest is compounded weekly,
Stated interest rate, i = 8.145%,
number of compounding periods, n = 1 week = 1,
[tex]r_w = (1 + \dfrac{i}{n} )^n - 1\\\\r_w = (1 + \dfrac{0.08145}{1} )^1 - 1\\\\r_w= 0.08145 = 8.145\%[/tex]
number of compounding periods, n = 1 year = 52 week = 52,
[tex]r_w = (1 + \dfrac{i}{n} )^n - 1\\\\r_w = (1 + \dfrac{0.08145}{52} )^{52} - 1\\\\r_w= 0.084789 = 8.4789\%[/tex]
Tiffany's effective interest rate be if the interest is compounded semiannually,
Stated interest rate, i = 8.145%,
number of compounding periods, n = for half year = 1,
[tex]r_s = (1 + \dfrac{i}{n} )^n - 1\\\\r_s = (1 + \dfrac{0.08145}{1} )^1 - 1\\\\r_s= 0.08145 = 8.145\%[/tex]
number of compounding periods, n = 2 semiannually = 2,
[tex]r_s = (1 + \dfrac{i}{n} )^n - 1\\\\ r_s = (1 + \dfrac{0.08145}{2} )^2 - 1\\\\ r_s= 0.0831 = 8.31\%[/tex]
Thus, for the first week and 1 semiannually, the effective interest rate will be the same but will definitely make a change, if seen for a year.
Therefore, Tiffany's effective interest rate if interest is compounded weekly rather than compounded semiannually will be [tex]r_w-r_s=(8.4789-8.31)% = 0.1689%[/tex].
Hence, option c is correct, 0.1689.
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