math
posted by Gaby .
On a set of bluepints the scale is half an inch=4feet
Find the actual lengthof a room that measures 2.8 inches on the blueprint

How many half inches are in 2.8 inches? that is how many 4 feet are in the room.
Feet in Room=4* 2.8/.5
check my thinking. 
16.8*2.8=47.04/5=9.4

How can the room be only 9.4 feet, when 1 inch = 8 feet?

I set up another porportion and cross multiplied, and i got what you told me...
8ft over 1in = x over 2.8 and I crossed multiplied to get 22.4 
Set up a proportion.
0.5 / 4 = 2.8 / x
Cross multiply.
0.5x = 4 * 2.8
0.5x = 11.2
x = 22.4