The given scale is:
1 in = 3 ft
The blueprint measurements:
length = L = 4.5 in
width = W = 3.75 in
To find the perimeter of the actual bedroom, we have to convert the scale to actual length and width.
The actual measurements:
length = L' = 4.5 * 3 = 13.5 feet. (as 1 in = 3 ft)
width = W' = 3.75 * 3 = 11.25 feet
The perimeter (P) of the rectangle is given by:
P = 2*( Length + Width)
or
P = 2* (L' + W')
P = 2* (13.5 + 11.25)
P = 2* (24.75)
P = 49.5 feet
Hence, the perimeter of the bedroom is 49.5 feet.