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匿名 發問於 科學及數學數學 · 5 年前

maths

Mr.Tang deposited $10000 in a bank at the beginning of 2012 and $9000 at the beginning of 2013. The interest was compounded yearly at r% p.a. , and total amount he received at the beginning of 2014 was $22000. Find r.

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  • 5 年前
    最愛解答

    10000(1+r%)²+9000(1+r%)=22000

    ==> 10(1+r%)²+9(1+r%)-22=0==> [10(1+r%)-11][(1+r%)+2]=0==> 1+r%=1.1 or -2 (rej)==> r%=0.1==> r=10

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