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Thread: precalculus formula

  1. #1
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    precalculus formula

    I don't know which formula to use for this problem. I was given these formulas to use by my teacher. this one is for monthly payment-> m.p= (A*P(1+R)^N)/((1+R)^N-1) the letters stand for M.P= monthly payment A= amount of the loan R= monthly interest rate (divide by 12) N= number of paymentsthis one is for ordinary annuity A=P(((1+R)^N -1)/(R))the letters stand for A = amount accumulated P= payment per period R= Rate per period N = number of paymentsthis one is for annuity due it is the same for ordinary annuityit is asking "What is the monthly payment on a 30 year mortgage of $100,000 at 8% interest per year compounded monthly?it also wants to know the total amount paid on this loan over the 30 year period.
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  2. #2
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    Re: precalculus formula

    Your "run together sentences" make this a little hard to read. But you appear to have one formula you say is for "monthly payment" and the other for "Amount accumulated". You question asked for "monthly payment" so shouldn't you use the first? You are also asked for "the total payment over 30 years". How many months are there in 30 years? Multiply that by the monthly payment.
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  3. #3
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    Re: precalculus formula

    The formulas are for "monthly payment" "ordinary annuity" & "annuity due". I will try the monthly payment then and post my answer here later to see if it is correct.
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  4. #4
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    Re: precalculus formula

    Quote Originally Posted by dtdj13 View Post
    The formulas are for "monthly payment" "ordinary annuity" & "annuity due". I will try the monthly payment then and post my answer here later to see if it is correct.
    You're trying to calculate the "monthly payment", so why
    d'hell wouldn't you use the "monthly payment formula"?!

    The formula you're showing:
    m.p= (A*P(1+R)^N)/((1+R)^N-1)
    is wrong...who gave you that?

    Should be:
    P = A*R / [1 - 1/(1 + R)^N]
    where:
    P = payment = ?
    A = amount = 100,000
    N = number of months = 360
    R = rate per month = .08/12
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  5. #5
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    Re: precalculus formula

    I see the problem now I was copying the formula down wrong.the correct formula is (A*R(1+R)^N)/((1+R)^N-1) the answer I got was 7999.999. I don't know how to find the total amount paid on this loan over the 30 year period.
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  6. #6
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    Re: precalculus formula

    Quote Originally Posted by dtdj13 View Post
    I see the problem now I was copying the formula down wrong.the correct formula is (A*R(1+R)^N)/((1+R)^N-1) the answer I got was 7999.999. I don't know how to find the total amount paid on this loan over the 30 year period.
    AGAIN, that is completely ridiculous.
    You're willing to pay $8000 per month for 30 years???
    I gave you the CORRECT formula: wake up, buddy...
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  7. #7
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    Re: precalculus formula

    I tried you formula amount got 733.764
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  8. #8
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    Re: precalculus formula

    to find the total amount due on the loan i multiplied 733.764 by 360 then got 264155.2466 but I don't know if that is right
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  9. #9
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    Re: precalculus formula

    Wow...you completely surprised me!

    264155.25 is correct;
    the interest is 264155.25 - 100000.00 = 164155.25;
    in other words, what is paid back less what is borrowed.
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  10. #10
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    Re: precalculus formula

    Thanks DenisB for helping me
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