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If an investment of d dollars is compounded continuously at an annual interest r

ID: 3284348 • Letter: I

Question

If an investment of d dollars is compounded continuously at an annual interest rate r, then the amount of money A(t) earned at time t > 0 (in years) is the solution of the initial value problem where r should be expressed as a fraction rather than as a percentage rate, e.g., an annual interest rate of r = 12% would be expressed as Suppose you have just placed d dollars in a bank account that pays 5 percent (annual) interest, compounded continuously. How much do you have in the account after 4 years? (Do not include dollar signs in your answer.) How long (in years) will it take your money to double? (c) How long (in years) will it take your money to triple?

Explanation / Answer

a) d*(e^.05*4)= 1.2214d b)2d= d(e^.05t) ln(2)/.05= t t= 13.86 years. c) 3d= d(e^.05t) ln(3)/.05=t t= 21.97 years. The above calculations have been done using 5% as that is what I feel should be used. However if the answer is revolving around 12, please change 05 to 12.