$\"\"$

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The Prinicipal Income is $\"\"$ .

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The purchased amount is $\"\"$

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The rate of inflation is $\"\"$

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Find the time period .

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Purchased amount is $\"\"$ .

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Substitute all the values in the equation.

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$\"\"$

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$\"\"$

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Apply natural logarithm on each side.

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$\"\"$

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$\"\"$

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$\"\"$

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Therefore, the time period is $\"\"$ years.

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$\"\"$

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The time period is $\"\"$ years.

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