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.