$\"\"$

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Initial investment is $\"\"$ .

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Find rate:

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Half life to find $\"\"$ .

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The general form of investment rate is $\"\"$ , where $\"\"$ is $\"\"$ and $\"\"$ is $\"\"$ .

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$\"\"$

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Take natural logarithm on both sides.

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$\"\"$

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Therefore, the annual rate is $\"\"$ .

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$\"\"$

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To find the Amount after $\"\"$ years :

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General form is $\"\"$

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Substitute plug for $\"\"$ for $\"\"$ , $\"\"$ and $\"\"$ in the general form.

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$\"\"$

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Therefore,the amount after $\"\"$ years is $\"\"$ .

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$\"\"$

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Annual rate is $\"\"$ is $\"\"$ .

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Amount after $\"\"$ years is $\"\"$ .