Answer
Federal tax owed: $\$5,027.50$
Marginal tax rate: $15\%$
Work Step by Step
From Table 16.1, ${$37,500}$ falls into the second tax bracket, which has a tax rate of 15%, so the amount of tax paid on this money is
$0.10\times 11,950=1,195$
$0.15\times (37,500-11,950)=3,832.50$
Total tax: $1,195+3832.50=\$5,027.50$
The marginal tax rate of your last dollar, which falls into the second bracket is $15\%$.
