In how many year the interest will became equal to the principal is rs.1200 is deposited at the rate of 25% in a bank ​

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In how many year the interest will became equal to the principal is rs.1200 is deposited at the rate of 25% in a bank ​

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Khải Quang 4 years 2021-09-05T16:07:07+00:00 1 Answers 13 views 0

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  1. trungdung22
    0
    2021-09-05T16:08:07+00:00
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    Given:

    Principal = Rs. 1200

    Rate of interest = 25%

    To find:

    The time in which the interest will became equal to the principal.

    Solution:

    We have,

    P=1200

    r=\dfrac{25}{100}

    r=0.25

    If interest is equal to the principal, then

    Amount=Principal+Interest

    Amount=1200+1200

    Amount=2400

    The formula for amount is:

    A=P\left(1+r)^n

    Substituting A=2400, P=1200, r=0.25 in the above formula, we get

    2400=1200(1+0.25)^n

    \dfrac{2400}{1200}=(1.25)^n

    2=(1.25)^n

    Taking log on both sides, we get

    \log2=\log(1.25)^n

    \log2=n\log(1.25)               [\because \log a^b=b\log a]

    \dfrac{\log2}{\log(1.25)}=n

    n\approx 3.11

    Therefore, the interest will became equal to the principal in about 3.11 years.

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