Why is la cuarta not acceptable if I am talking about the fourth mujer or falda?
The word fourth at this lesson isn't correct. This lesson is for places. And the correct term for a place in english would be the "bedroom" and the translation "habitacion" or "cuarto". Fourth is an ordinal number in english, not a place, Like this: "the fourth place in a race" is the same of "La cuarta posición en una carrera".