If Hermione pays $10.00 in taxes on $100 of income and $10.25 on $101 of income, which of the following is not true?

Question

Quizplus · Accepted Answer

Since Hermione pays $10.00 in taxes on $100 of income and $10.25 on $101 of income, her marginal tax rate at $100 is equal to the change in taxes over the change in income, which is ($10.25-$10.00)/($101-$100) = 25%. Therefore, statement A is true. 
Her average tax rate at $100 is the total taxes paid divided by total income, which is ($10.00)/($100) = 10%. Therefore, statement B is also true. 
She faces a progressive tax because her tax rate increases as her income increases. Therefore, statement C is also true. 
However, her marginal tax rate at $100 is not 10.25%, which is the rate she pays on income above $100. Her marginal tax rate at $100 is 25%, as calculated earlier. Therefore, statement D is not true.

If Hermione Pays $10