Final answer:
Shirley's 401K value after 25 years of monthly $75 contributions with a 6% annual interest rate compounded monthly is $49,378.05, calculated using the future value of an annuity formula.
Step-by-step explanation:
To calculate the value of Shirley's 401K after 25 years of contributing $75 every month with an interest rate of 6% compounded monthly, we can use the future value of an annuity formula:
FV = P × ((1 + r)^n - 1) / r
Where:
- FV is the future value of the annuity.
- P is the periodic payment amount ($75 in this case).
- r is the monthly interest rate (6% per year or 0.06, divided by 12).
- n is the total number of payments (25 years × 12 months per year).
Firstly, we convert the annual interest rate to a monthly rate:
r = annual interest rate / number of compounding periods per year
= 0.06 / 12
= 0.005
Next, we calculate the total number of payments:
n = number of years × number of compounding periods per year
= 25 × 12
= 300
Then, we plug these figures into the formula:
FV = $75 × ((1 + 0.005)^300 - 1) / 0.005
Calculation:
FV = $75 × ((1.005)^300 - 1) / 0.005
= $75 × (4.291870 - 1) / 0.005
= $75 × 3.291870 / 0.005
= $75 × 658.374
= $49,378.05
After 25 years, the final value of Shirley's 401K is $49,378.05.