3. march deposited money into an account in which interest is compounded quarterly at a rate of 3.3%. how much did he deposit if the total amount in his account after 21 months was $4369.20, and he made no other deposits or withdrawals?

$4125.

Step-by-step explanation:

When solving for the principal we still need to use the formula .

Let's take all the variables that we do have available and list them out.

A = $4369.20

r = 3.3% or 0.033

n = 4 (Quarterly)

t = 21 months or 1.75 years

Now we can substitute the values and solve for the principal.

Now we need to divide both sides with 1.05919912849  to get the principal.

P = 4125.00339406 or $4125.

To check for our answer, we can simply substitute the values including the principal and excluding the total.

or

3x^3-x^2+6x-9