To find out how long it will take Stacy to paint the entire room, we first determine her painting rate.
Stacy can paint 3/4 of the bedroom in 3 hours.
To find her rate of painting, we calculate how long it takes her to paint 1/4 of the room:
If she paints 3/4 in 3 hours, then:
\[ \text{Time for } 1/4 = \frac{3 \text{ hours}}{3} = 1 \text{ hour} \]
Now, since it takes her 1 hour to paint 1/4 of the room, we can find out how long it will take her to paint the entire room (which is 4 quarters):
\[ \text{Time for whole room} = 1 \text{ hour/quarter} \times 4 = 4 \text{ hours} \]
So, it will take Stacy 4 hours to paint the entire room.