Answer-
The total cost of his purchase will be $3,846.34
Solution-
Here, the annual interest rate is 17.45%.
So monthly interest rate will be,
[tex]=\frac{17.45}{12} =1.454\%=0.01454[/tex]
With a purchase of $3,740, the amount will be after one month,
[tex]=3740(1+0.01454)^1=3740(1.01454)=3794.38[/tex]
Then she makes a payment of $1350, so the balance at the end of month 1 is
[tex]=3794.38-1350=2444.37[/tex]
Now she has to pay with $2444.37 as principal amount, the amount will be after one month,
[tex]=2444.37(1+0.01454)^1=2444.37(1.01454)=2479.91[/tex]
Then she again makes a payment of $1350, so the balance at the end of month 2 is
[tex]=2479.91-1350=1129.91[/tex]
Final month, she has to pay with $1129.91 as principal amount, the amount will be,
[tex]=1129.91(1+0.01454)^1=1129.91(1.01454)=1146.34[/tex]
So the total cost, including interest, would be the sum of the three payments,
[tex]=1350+1350+1146.34=3,846.34[/tex]