Answer: The actual length of a room that measures 2.8 inches on the blueprint will be 22.4 feet.
Step-by-step explanation:
We are given that ,
On a set of blueprints, the scale is 
Multiply 2 both sides , we get
Then, 


Then, the actual length of a room that measures 2.8 inches on the blueprint. will be 22.4 feet.
Hence, the correct answer is 22.4 feet.