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Thread: Series and Sequence question

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    Series and Sequence question

    Hi,

    Can anyone please help me solve these two questions from Maths in Focus?

    ThanksScreen Shot 2018-01-19 at 8.33.45 pm.pngScreen Shot 2018-01-19 at 8.34.06 pm.png

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    Re: Series and Sequence question

    The question is somewhat ambiguously worded but I will assume the meaning to be "decreasing by 5% of the previous year's population".

    Use the formula for geometric sequences.

    Let be the population, expressed as a percentage of the original, at the start of the th year (be careful with wording).





    (decreasing by 5% is the same as taking 95%)

    You can do the first question with simple substitution. The other two can be done with a substutition and then rearranging to make the subject (logarithms will be required).
    HSC 2018: English Adv. [80] • Maths Ext. 1 [98] • Maths Ext. 2 [95] • Chemistry [87] • Software Design [95]

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    Re: Series and Sequence question

    Thank you

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