I updated the Practical Application file
this morning. For question 4, both parts c and d should be based on 25 years. The comparison here is the PV of an annuity and an annuity due, keeping time, interest rate, and payments the same.
However i am going to send you some other practice questions and solutions so that you see how the professor solved the compare to the one you send to me
If the writer can use BA II Financial Calculator to solve the problems following the steps as used by the lecturer that will be fine