Final answer:
Rebecca would need to save money for approximately 22.25 years to have enough money to start college
Step-by-step explanation:
To calculate the time it would take for Rebecca to save enough money to start college, we can use the future value formula for compound interest:
FV = P(1 + r/n)^(nt), where
FV is the future value,
P is the principal (starting amount),
r is the annual interest rate,
n is the number of times interest is compounded per year, and
t is the number of years.
In this case, P = $0, r = 6% or 0.06, n = 12 (compounded monthly), and FV = $20,000. Plugging these values into the formula, we get:
$20,000 = 0.06/12 * (1 + 0.06/12)^(12t)
To solve for t, we can use logarithms. First, divide both sides of the equation by $0.06/12:
$20,000 / ($0.06/12) = (1 + 0.06/12)^(12t)
Next, take the natural logarithm (ln) of both sides:
ln($20,000 / ($0.06/12)) = ln((1 + 0.06/12)^(12t))
Using properties of logarithms, we can bring down the exponent:
ln($20,000 / ($0.06/12)) = 12t * ln(1 + 0.06/12)
Now, divide both sides by 12 * ln(1 + 0.06/12) to solve for t:
t = ln($20,000 / ($0.06/12)) / (12 * ln(1 + 0.06/12))
Using a calculator, t is approximately 22.25 years.
Therefore, it would take Rebecca around 22.25 years to have enough money to start college.