A. After 12 years, the average cost of college is estimated to be approximately $67,455.83 per year, given an annual increase of 8.2%. B. To cover 1 year of college in 12 years, invest approximately $14,711.94 now at a 5.5% continuous compound interest rate.
Let's solve each part of the problem step by step:
(a) Average Cost Increase:
- The formula for compound interest is
, where:
- A is the future value,
- P is the principal (initial amount),
- r is the annual interest rate (in decimal form),
- n is the number of times interest is compounded per year,
- t is the number of years.
- For this problem, P is the current average cost, r is the annual increase rate, and t is the number of years.
- The future average cost after 12 years is
.
(b) Savings Plan:
- For continuous compounding, the formula is
, where:
- A is the future value,
- P is the principal,
- e is the mathematical constant approximately equal to 2.71828,
- r is the interest rate,
- t is the time in years.
- Rearrange the formula to find \(P = \frac{A}{e^{rt}}\).
- The amount needed in the savings plan now is
.
Let's calculate the final answers:
(a) Average Cost Increase:
-

(b) Savings Plan:
-

After 12 years, the average cost of college will be approximately $67,455.83 per year. To pay for 1 year of college 12 years from now, you should put approximately $14,711.94 in the savings plan now.