Results 1 to 5 of 5

Math Help - rearranging this formula

  1. #1
    da`
    da` is offline
    Newbie
    Joined
    Oct 2008
    Posts
    22

    rearranging this formula

    Hello,

    I have just tried to put together a formula for savings which is attached below.

    I have it for such a question
    ___________________________________

    I put in a lump sum amount of 3,500 into a new account. I also will be paying 900 of my wage per month into this account for 5 years. The gross interest rate will be 5%. How much will I end up with after this time?

    where the answer is

    γ = 3,500
    α = 0.05
    t = 5
    β = 900

    F=((γ)(exp^(αt)))+((β)((exp^(αt))-1)/(exp^(α/12))-1))

    F = (( 3,500 )(exp^(0.05x5))) + (( 900 )(( exp^(0.05x5)) - 1)/( exp^(0.05/12)) -1 ))

    F = (3500 x (1.284)) + ((900 x (((1.284) 1)/((1.004)-1))

    F = 4494.089 + (900 x (68.024))

    F = 4494.089 + 61221.767

    F = 65,715.86

    Therefore I will have saved 65,715.86.

    ____________________________________

    Firstly is this formula correct? Because I have noticed in this calculator SAVINGS CALCULATOR ... I am getting a different figure. I have noticed that this Halifax calculator is missing the final months interest. So the question is, is my formula right? and if so can someone help me in re-arranging this formula, to solve for t and to solve for β as it is giving me a headache.

    Thanks alot.
    Attached Thumbnails Attached Thumbnails rearranging this formula-savings.jpg  
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Dec 2007
    From
    Ottawa, Canada
    Posts
    3,080
    Thanks
    66
    If the 5% compounds monthly (i = .05/12) and the 1st 900 deposit is
    1 month after the initial deposit of 3500, then answer is 65,697.23

    i = .05/12:

    3500(1 + i)^60 = 4491.76

    900[(1 + i)^60 - 1] / i = 61205.47 ; add 'em to get 65,697.23
    Follow Math Help Forum on Facebook and Google+

  3. #3
    da`
    da` is offline
    Newbie
    Joined
    Oct 2008
    Posts
    22
    excellent. thank you

    now with this formula

    F=((γ)(1+i)^12t) + ((β/i)((1 + i)^12t) - 1))

    how do I rearrange this to solve for t?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    da`
    da` is offline
    Newbie
    Joined
    Oct 2008
    Posts
    22
    ignore my last post mate.

    thanks alot
    Follow Math Help Forum on Facebook and Google+

  5. #5
    MHF Contributor
    Joined
    Dec 2007
    From
    Ottawa, Canada
    Posts
    3,080
    Thanks
    66
    Quote Originally Posted by da` View Post
    F=((γ)(1+i)^12t) + ((β/i)((1 + i)^12t) - 1))
    how do I rearrange this to solve for t?
    Using this rule:
    If a^p = x, then p = log(x) / log(a)
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Rearranging the formula
    Posted in the Algebra Forum
    Replies: 2
    Last Post: May 7th 2011, 09:26 PM
  2. rearranging formula
    Posted in the Algebra Forum
    Replies: 24
    Last Post: May 3rd 2011, 02:14 PM
  3. rearranging formula
    Posted in the Algebra Forum
    Replies: 2
    Last Post: November 22nd 2010, 05:22 PM
  4. Rearranging formula
    Posted in the Algebra Forum
    Replies: 1
    Last Post: December 18th 2008, 07:10 AM
  5. Rearranging formula help
    Posted in the Algebra Forum
    Replies: 1
    Last Post: November 7th 2008, 08:40 AM

Search Tags


/mathhelpforum @mathhelpforum