Answer:
4.5 foot is needed for a unit dozen bird house 
Step-by-step explanation:
Given Tina saw ¾ foot of wooden trim is being used for first 1/6 dozen bird houses 
Therefore, we can write as,4 
1/6 dozen = ¾ foot 
For 1 dozen bird houses, we have to use the unitary method 
1/6 dozen = ¾ foot 
Therefore, 1 dozen or unit dozen = 

1 dozen = ¾ * 6 = 
 foot = 4.5 foot
 foot = 4.5 foot 
Therefore, 4.5 foot is needed for a unit dozen bird house