If Stacy can paint \( \frac{3}{4} \) of the bedroom in 3 hours, we can first determine her painting rate per hour.
To find her rate, divide the portion of the room she can paint by the time taken:
\[ \text{Rate} = \frac{\frac{3}{4} \text{ (room)}}{3 \text{ hours}} = \frac{3}{4} \div 3 = \frac{3}{4} \times \frac{1}{3} = \frac{3}{12} = \frac{1}{4} \text{ (room per hour)} \]
Now we know Stacy can paint \( \frac{1}{4} \) of the room in one hour. To find how long it takes her to paint the entire room, we need to calculate the time for 1 room:
\[ \text{Time} = \frac{1 \text{ (room)}}{\frac{1}{4} \text{ (room per hour)}} = 1 \times 4 = 4 \text{ hours} \]
Therefore, it will take Stacy 4 hours to paint the entire room.