$\"\"$

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(a).

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Compounding interest compounded continuously $\"\"$ .

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Find the time taken to double the invested amount.

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Rate of interest is $\"\"$ .

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Hence, $\"\"$ at $\"\"$ .

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Substitute $\"\"$ and $\"\"$ in the equation $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ .

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After $\"\"$ years, the amount will be double of the invested amount.

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$\"\"$

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(b).

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Find annual interest rate.

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Interest rate $\"\"$ .

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Substitute $\"\"$ and $\"\"$ .

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For annully $\"\"$ in the above equation.

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$\"\"$

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$\"\"$

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Apply logrithm on each side.

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$\"\"$

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Power property of logarithm : $\"\"$ .

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$\"\"$

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The annual interest rate is $\"\"$ %.

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$\"\"$

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(a) After $\"\"$ years, the amount will be double of the invested amount.

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(b) The annual interest rate $\"\"$ %.