Amount Financed(P) = $ 128,000
Time = 15 year
Rate of interest= 5.05%
Amount after 15 years translates to,
[tex]{\text{Using the formula}} P(1+\frac{R}{100})^n\\\\ 128,000(1 +\frac{5.05}{100})^{15}\\\\ =128,000 \times (1.0505)^{15}\\\\=128,000 \times 2.0938\\\\=268,009.890[/tex]
Rose and Andrew has taken four points to lower their rate to 4.81% .
Amount after 15 years translates to, if rate of interest is 4.83 %
[tex]{\text{Using the formula}} P(1+\frac{R}{100})^n\\\\ 128,000(1 +\frac{4.83}{100})^{15}\\\\ =128,000 \times (1.0483)^{15}\\\\=128,000 \times 2.0290\\\\=259713.0404[/tex]
Cost of four points = 268,009.890 - 259,713.0404
= $8296.8496