Question 1 Answer: 1cm= 3 feet. I say this because if there is 5 cm on the blueprint, you can do 3 feet for every cm and get 15 feet.
Question 2 Answer: 1 in=1.5 feet. 6÷4= 1.5 therefore the scale factor is 1.5
I can't quite see the other answers if you could zoom in i could answer those as well.