To determine the amount Derek must contribute to his retirement account from his 26th to his 65th birthday so that he can reach $2,506,064.00 by the end of year following his 75th birthday, we need to perform several calculations involving future values of annuities and investment growth.
Step 1: Determine the Future Value Requirement
Derek wants to have $2,506,064.00 in his retirement account at the end of the year following his 75th birthday. This means he needs this amount when he is 76 years old.
Step 2: Working Back to His 65th Birthday
Since Derek's investments will grow at an interest rate of 4.00%, we can calculate how much he needs when he turns 65. He will not make any more contributions after age 65, but the money in the account will continue to grow until he is 76.
Calculate the Growth of the Account from Age 65 to Age 76:
The time between age 65 and age 76 is 11 years. We can use the future value formula to determine how much Derek needs to have in his account when he turns 65 to reach his goal at age 76:
\[ FV = PV \times (1 + r)^n \]
Where:
- \( FV = 2,506,064.00 \)
- \( r = 0.04 \) (the interest rate)
- \( n = 11 \) years
Rearranging the formula to find \( PV \) (the amount he needs at age 65):
\[ PV = \frac{FV}{(1 + r)^n} \]
Plug in the numbers:
\[ PV = \frac{2,506,064.00}{(1 + 0.04)^{11}} = \frac{2,506,064.00}{(1.04)^{11}} = \frac{2,506,064.00}{1.48024} \approx 1,692,456.92 \]
So, Derek must have approximately $1,692,456.92 in his retirement account when he turns 65.
Step 3: Determine Contributions from Age 26 to Age 65
Next, we need to determine how much Derek should contribute annually to reach this amount by his 65th birthday. He will contribute from age 26 to age 65, which is a total of \( 65 - 26 + 1 = 40 \) years.
We can use the future value of an annuity formula for contributions:
\[ FV = PMT \times \frac{(1 + r)^n - 1}{r} \]
Where:
- \( FV = 1,692,456.92 \) (the amount needed at age 65)
- \( PMT \) = annual contribution
- \( r = 0.04 \)
- \( n = 40 \)
Rearranging the formula to find \( PMT \):
\[ PMT = \frac{FV \times r}{(1 + r)^n - 1} \]
Now plug in the numbers:
\[ PMT = \frac{1,692,456.92 \times 0.04}{(1 + 0.04)^{40} - 1} \]
First, calculate \( (1 + 0.04)^{40} \):
\[ (1.04)^{40} \approx 5.21068 \]
Now calculate \( (1.04)^{40} - 1 \):
\[ 5.21068 - 1 = 4.21068 \]
Now plug everything back into the equation for \( PMT \):
\[ PMT = \frac{1,692,456.92 \times 0.04}{4.21068} \approx \frac{67,698.2768}{4.21068} \approx 16,069.31 \]
Conclusion
Derek must contribute approximately $16,069.31 annually from his 26th birthday to his 65th birthday in order to reach his retirement goal of $2,506,064.00 by the time he is 76 years old.