Jack has taxable income of $65,000. He is a single tax filer, and his federal income tax rates on the first $8,350 is 10%; it is 15% on income from $8,350 to $33,950 and 25% on income from $33,950 up to $82,250. What is Jack's federal income tax liability, what is his marginal rate, and why would he care? Finally, what is his average federal tax rate?