A couple plans to save for their child’s college education. What principal must be deposited by the parents when their child is born in order to have $100,000 when the child reaches age 18? Assume the money earns 4% interest, compounded quarterly.

p(1+.04/4)^(4*18) = 100000

p = 48849.61

To find the principal amount that needs to be deposited by the parents when their child is born, you need to use the formula for compound interest:

A = P(1 + r/n)^(nt)

Where:
A is the future value of the investment ($100,000 in this case)
P is the principal amount (what we need to find)
r is the annual interest rate (4% or 0.04 in decimal form)
n is the number of times the interest is compounded per year (quarterly compounding means n = 4, as there are 4 quarters in a year)
t is the number of years

In this case, the investment period is 18 years.

Plugging in the values we have into the formula, we get:

$100,000 = P(1 + 0.04/4)^(4*18)

Simplifying this equation, we need to solve for P.

First, let's simplify the exponent:

$(1 + 0.01)^(4*18)

Next, let's simplify the exponent further:

$(1.01)^72

Now, calculate the value of (1.01)^72:

(1.01)^72 = approximately 2.857263378

Now, our equation becomes:

$100,000 = P * 2.857263378

To find P, we can divide both sides of the equation by 2.857263378:

P = $100,000 / 2.857263378

P ≈ $34,927.04 (rounded to the nearest dollar)

Therefore, the couple needs to deposit approximately $34,927 when their child is born in order to have $100,000 when the child reaches 18 years of age.