In: Finance
2. An investment of $425 is made at a nominal rate of 4% per year, with interest compounded monthly. How long will it take that investment to double?
a) Write the equation that you need to solve in order to answer this problem.
b) Show how to solve your equation TWO ways: graphically and symbolically. To solve graphically, clearly sketch the window you saw, give the dimensions of the window, label your curves, and give the coordinates of any point(s) of importance.
When solving symbolically, I want you to first find the EXACT answer, and then give an appropriate decimal approximation.
You may use natural logs and/or common logs, but logs of no other bases. Be sure the answer to the question asked is stated in a short sentence at the end of your work.
. In order to compute the timeframe in which the investment doubles , we need to compute the APR effective rate and use the TVM or time value of money considerations to find the time in which the investment doubles
In order to calculate the effective annual rate we have
Eff rate ( 1+nom rate /m )^m -1 where m is the number compoundings
We have a nominal rate of 4% pa
M = monthly compoundings 12
So Eff rate = 4.074% pa.
So as per TVM considerations
PV = FV (1+R)^N
Or
425 = 2x425 (1+0.04074)^n
Taking Log ( Natural Logarithm )
We have
Log ( 0.5) = n x log (1.04074)
Or n = 17.358189 years
Approximated to 2 decimals we have 17.36 years
If we plot the equation graphically
YEAR |
PV |
INTEREST |
FV |
Times |
1 |
425 |
17.3145 |
442.3145 |
1.04074 |
2 |
442.3145 |
18.01989 |
460.3344 |
1.08314 |
3 |
460.3344 |
18.75402 |
479.0884 |
1.127267 |
4 |
479.0884 |
19.51806 |
498.6065 |
1.173192 |
5 |
498.6065 |
20.31323 |
518.9197 |
1.220988 |
6 |
518.9197 |
21.14079 |
540.0605 |
1.270731 |
7 |
540.0605 |
22.00206 |
562.0626 |
1.3225 |
8 |
562.0626 |
22.89843 |
584.961 |
1.376379 |
9 |
584.961 |
23.83131 |
608.7923 |
1.432452 |
10 |
608.7923 |
24.8022 |
633.5945 |
1.490811 |
11 |
633.5945 |
25.81264 |
659.4071 |
1.551546 |
12 |
659.4071 |
26.86425 |
686.2714 |
1.614756 |
13 |
686.2714 |
27.9587 |
714.2301 |
1.680541 |
14 |
714.2301 |
29.09773 |
743.3278 |
1.749007 |
15 |
743.3278 |
30.28318 |
773.611 |
1.820261 |
16 |
773.611 |
31.51691 |
805.1279 |
1.894419 |
17 |
805.1279 |
32.80091 |
837.9288 |
1.971597 |
18 |
837.9288 |
34.13722 |
872.066 |
2.05192 |
19 |
872.066 |
35.52797 |
907.594 |
2.135515 |
20 |
907.594 |
36.97538 |
944.5694 |
2.222516 |
The graph obtained as follows
The point in FV at the doubling point can be seen from the graph
Thanks