How much money invested at 5% compounded continuously for 3 years will yield $820?

P=820:e^ (0.05*3)

P=705.7

Percentage of interest at which the money is invested = 5%

Time for which the money is invested = 3 years

The final amount after 3 years = $820

Let us assume the principal amount = x dollars

Then

820 = x (1 + 0.5) ^3

820 = x (1.05) ^3

x = 820 / (1.05) ^3

= 708.35 dollars

From the above deduction, we can conclude that the principal amount invested was $708.35.