Nicholas uses a credit card with a 19.1% APR, compounded monthly, to pay for a cruise totaling $2,513.69. He can pay $910 per month on the card. What will the total cost of this purchase be?
is the credit card his?
Yes
We have 19.1% APR, which is the annual rate What is the monthly rate?
$2.993.80 $2,513.69 $3,285.64 $2,591.95 these are the choices it gives
hint: monthly rate = (APR)/12
So 910=(.191)/12
?
what does your calculator say when you type in 0.191/12
0.015
I'm getting 0.01591666666667 Let's round that to 0.0159167 just to keep things relatively simple
now multiply that with 2,513.69 and tell me what you get
40.0095658
I'm getting the same. Let's round that to 40.01 since money is usually rounded to the nearest cent (hundredth)
Okay
The 40.01 is the amount of interest for the month The balance 2513.69 jumps up to 2553.70 after we add on the 40.01 In other words, 2513.69+40.01 = 2553.70
So we started with a balance of 2513.69 and now the balance is 2553.70
Correct
Then the payment of $910 will lower the balance to 2553.70-910 = 1643.70 With me so far?
Yes
ok that was all for month #1
we will repeat this process for month #2
start with a balance of 1643.70 and find the monthly interest you'll pay So you'll need to multiply 1643.70 with 0.0159167
26.16227979
that rounds to 26.16
Add that onto the balance and you get what?
1,669.86?
correct
now subtract off the monthly payment of $910
759.86
correct we'll need to do one more round of this
Ok
if the balance is 759.86, what is the monthly interest we pay for month #3?
How do I get that
multiply 759.86 with the value 0.0159167
since 0.0159167 was the monthly rate (in decimal form)
monthly interest = (current balance)*(decimal form of monthly rate)
Multiply by 759?
759.86 * 0.0159167 = ??
12.09
yes, so the balance goes from 759.86 to 759.86+12.09 = 771.95 Agreed?
Yes
At this point, we would subtract off the payment of $910 However, this payment is larger than the current balance So we can just pay off the entire balance and bring it to 0 This means the final payment is $771.95 instead of $910
Throughout this process, you should be keeping track of all the values in a chart like you see below
Oh okay
The table is handy to see how much you pay on a given month, and what your balance is, etc
what do you get when you add up the stuff in the "payment" column?
So add everything?
just in the payment column
doing so will lead to the total cost, since it's the sum of all the payments
2,591.95
correct
so the answer is choice D
Thank you
If you're curious about the total interest paid, then you subtract the total cost and cost of the product 2591.95 - 2513.69 = 78.26 The total interest is $78.26
no problem
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