Answer:
28 million are in Mankiwland's Labor force
Step-by-step explanation:
The Department of Labor defines the labor force (in simplified terms) as anyone who is employed, or unemployed (available to work; searching for work).
The labor force count excludes institutionalised (prisoners, retirees in retirement homes, etc.) and discouraged workers (able to work, but have no interest to seek employment).
Because if this, only the employed population (25 million) and the unemployed population (3 million) ate counted, adding up to a labor force of 28 million.