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How much interest would have been paid if....

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......£2.50 was saved in an ordinary bank savings account every Friday since 1997, with no withdrawals ? Genuine query. I need to know roughly how much interest was lost during this period, although I realise it wont be very much.

I know it is very much a 'how long is a piece of string' type question but even a ball park figure would help. Maths was never my strong point and I glaze over when I need to work stuff like this out..

No idea how much the actual interest rate was during this time but it was an ordinary RBS kids Rainbow account and the rate now is 4.10%.

Looked back and there were 459 Fridays from Jan 1997 till now. :D (£1,147.50)

Can anyone even give me an idea please? As I said... even ballpark would help.

TIA.
Herman - MP for all! :)

Comments

  • grumbler
    grumbler Posts: 58,629 Forumite
    Part of the Furniture 10,000 Posts Name Dropper Photogenic
    Well, average interest rate for your data is 5.2%(*). I think this is about the same as average interest rate of best saving accounts. For account with 6% average interest rate the resulting amount would be £1501 - just about £50 more than you have.

    The formula for todays balance is A*q*(q^n-1)/(q-1) where
    A=2.5;
    n=459;
    q=(1+i/100)^(1/52);
    i - annual interest %.

    See also ISA query ? estimated value needed...

    *EDIT: mistake. See my post #5 below.
  • Ball park figure ZERO
    ...............................I have put my clock back....... Kcolc ym
  • aliasojo
    aliasojo Posts: 23,053 Forumite
    Part of the Furniture 10,000 Posts Combo Breaker
    Thanks grumbler, I apreciate you taking the time to help. Just want to check though....the £1501 figure is £353.50 more than my original figure, not £50 more. The £1501 figure is the right one though?

    Thanks too for the formula....only I glazed on the first line. :o
    Herman - MP for all! :)
  • grumbler
    grumbler Posts: 58,629 Forumite
    Part of the Furniture 10,000 Posts Name Dropper Photogenic
    aliasojo wrote:
    Thanks grumbler, I apreciate you taking the time to help. Just want to check though....the £1501 figure is £353.50 more than my original figure, not £50 more. The £1501 figure is the right one though?

    Thanks too for the formula....only I glazed on the first line. :o
    Oops... mistake ... sorry :o
    5.2% is for £1447 not for £1147
    more correct results:

    3% - £1311
    4% - £1372
    5% - £1435
    6% - £1501
  • aliasojo
    aliasojo Posts: 23,053 Forumite
    Part of the Furniture 10,000 Posts Combo Breaker
    That's great, thank you again. Very helpful to have an idea of the kind of figures involved.
    Herman - MP for all! :)
  • Stonk
    Stonk Posts: 937 Forumite
    aliasojo wrote:
    I need to know roughly how much interest was lost during this period

    Are you working out how much you "lost" as a result of having one-too-many every Friday night?

    :beer:
  • aliasojo
    aliasojo Posts: 23,053 Forumite
    Part of the Furniture 10,000 Posts Combo Breaker
    I wish! :rotfl:
    Herman - MP for all! :)
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