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anonymous

  • one year ago

Find the doubling time of a quantity that is increasing by 9.8% per year.

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  1. Haseeb96
    • one year ago
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    lets suppose time = x then double time = 2x okay ???

  2. anonymous
    • one year ago
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    t = log 2/log 1.08 = 9.006468 years

  3. anonymous
    • one year ago
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    Why log 1.08?

  4. welshfella
    • one year ago
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    yea where did you get that from?

  5. anonymous
    • one year ago
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    Somebody help, I'm confused :(

  6. anonymous
    • one year ago
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    i gave you the answer i cant give you the show work to

  7. welshfella
    • one year ago
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    oops guys I must apologise I had it the wrong way round! you divide the rate into 72 so it is 72 / 9.8 = 7.35 years

  8. anonymous
    • one year ago
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    That's wrong @welshfella

  9. anonymous
    • one year ago
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    @kinggg How did you get log 1.08? Where did the number 1.08 come from?

  10. welshfella
    • one year ago
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    how do you know its wrong?

  11. anonymous
    • one year ago
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    I entered it and it said answer is NOT CORRECT

  12. anonymous
    • one year ago
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    @kinggg 9.006468 years is incorrect too

  13. welshfella
    • one year ago
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    i think the log formula is ln2 / ln(1.098)

  14. welshfella
    • one year ago
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    that gives 7.41 years

  15. anonymous
    • one year ago
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    7.41 years is correct!

  16. welshfella
    • one year ago
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    Lets do it the long way teh suppose the principle is $100 we have double amount 200 = 100(1 + 0.098)^n (1.098)^n = 2 take logs:- n ln 1.098 = ln n = ln 2 / ln1.098) = 7.41

  17. anonymous
    • one year ago
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    are you doing Exponential growth, doubling time

  18. welshfella
    • one year ago
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    rounding that up its 8 years

  19. anwaarullah
    • one year ago
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    8 years ,, let 100 be the investment so 100*1.098=,,,,,

  20. welshfella
    • one year ago
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    yea

  21. welshfella
    • one year ago
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    i guess that the interest is paid at the end of the year so that would make it 8.

  22. anonymous
    • one year ago
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    Thanks all!

  23. welshfella
    • one year ago
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    yw

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