Help! I need help arriving at the correct solution in the provided scenarios and need explanations. I would appreciate it.

Apply the imputed interest rules in the following situations

a. Mike loaned his sister Shonda $90,000 to buy a new home. Mike did not charge interest on the loan. The Federal rate was 4%. Shonda earned $900 of investment income for the year.

b. Nicos employer maintains an emergency loan fund for its employees. During the year, Nicos wife was very ill, and they incurred unusually large medical expenses. He borrowed $8,500 from his employers emergency loan fund for six months. The Federal rate was 4%. Nico and his wife earned no investment income for the year.

c. Jody borrowed $25,000 from her controlled corporation for six months. She used the funds to pay her daughters college tuition. The corporation charged Jody 3% interest. The Federal rate was 4%. Jody earned $3,500 of investment income for the year. d. Kait loaned her son, Jake, $60,000 for six months. Jake used the $60,000 to pay off college loans. The Federal rate was 4%, and Kait did not charge Jake any interest. Jake earned dividend and interest income of $2,100 for the tax year.