Mrs. Kirk withdrew $30,000 from a retirement account and used the money to furnish her new home. Her marginal tax rate is 24 percent. Compute the tax cost of the withdrawal in each of the following cases:

a. Mrs. Kirk is 56 years old. She withdrew the money from a personal savings account.

b. Mrs. Kirk is 56 years old. She withdrew the money from her employer-sponsored qualified plan upon her retirement from the company.

c. Mrs. Kirk is 56 years old. She withdrew the money from her employer-sponsored qualified plan, but she intends to work for the employer for at least 10 more years.

d. Mrs. Kirk is 61 years old. She withdrew the money from her employer-sponsored qualified plan, but she intends to work for the employer for at least 4 more years.

Assume the taxable year is 2018.