How much money has to be invested at 3.3% interest compounded continuously to have $45,000 after 19 years?

We calculate first the effective interest given the terms in this item.
                                  ieff = e^r - 1
(effective interest formula here is for compounded continuously cases only)
                                  ieff  = e^(0.033) - 1 = 0.03355
The future worth of current investment is calculated through,
                             F = P x (1 + ieff)^n
Substituting,
                               $45,000 = P x (1 + 0.033)^19
The value of P is $24,283.23.