Answer:
Part A)
About $3767.34.
Part B)
About $3692.47.
Step-by-step explanation:
Part A)
Recall that compound interest is given by the formula:
![\displaystyle A = P\left(1+\frac{r}{n}\right)^{nt}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20A%20%3D%20P%5Cleft%281%2B%5Cfrac%7Br%7D%7Bn%7D%5Cright%29%5E%7Bnt%7D)
Where <em>A</em> is the final amount, <em>P</em> is the initial amount, <em>r</em> is the interest rate, <em>n</em> is the number of times compounded per year, and <em>t</em> is the number of years.
To obtain $4000 after two years, let <em>A</em> = 4000 and<em> t</em> = 2.
Because the account pays 3% interest compounded monthly, <em>r</em> = 0.03 and <em>n</em> = 12.
Substitute and solve for <em>P: </em>
<em />![\displaystyle \begin{aligned} (4000) & = P\left(1+\frac{(0.03)}{(12)}\right)^{(12)(2)} \\ \\ P & = \frac{4000}{\left(1+\dfrac{(0.03)}{(12)}\right)^{(12)(2)}} \\ \\ & \approx \$3767.34\end{aligned}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5Cbegin%7Baligned%7D%20%284000%29%20%26%20%3D%20P%5Cleft%281%2B%5Cfrac%7B%280.03%29%7D%7B%2812%29%7D%5Cright%29%5E%7B%2812%29%282%29%7D%20%5C%5C%20%5C%5C%20P%20%26%20%3D%20%5Cfrac%7B4000%7D%7B%5Cleft%281%2B%5Cdfrac%7B%280.03%29%7D%7B%2812%29%7D%5Cright%29%5E%7B%2812%29%282%29%7D%7D%20%5C%5C%20%5C%5C%20%26%20%5Capprox%20%5C%243767.34%5Cend%7Baligned%7D)
In concluion, about $3767.34 should be deposited.
Part B)
Recall the formula for continuous compound:
![\displaystyle A = Pe^{rt}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20A%20%3D%20Pe%5E%7Brt%7D)
Where <em>e</em> is Euler's number.
Hence, let <em>A</em> = 4000, <em>r</em> = 0.04 and <em>t</em> = 2. Substitute and solve for <em>P: </em>
<em />![\displaystyle \begin{aligned}(4000) & = Pe^{(0.04)(2)} \\ \\ P & = \frac{4000}{e^{(0.02)(4)}} \\ \\ & \approx \$3692.47 \end{aligned}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5Cbegin%7Baligned%7D%284000%29%20%26%20%3D%20Pe%5E%7B%280.04%29%282%29%7D%20%5C%5C%20%5C%5C%20P%20%26%20%3D%20%5Cfrac%7B4000%7D%7Be%5E%7B%280.02%29%284%29%7D%7D%20%5C%5C%20%5C%5C%20%26%20%5Capprox%20%5C%243692.47%20%5Cend%7Baligned%7D)
In conclusion, about $3692.47 should be deposited.