SOLUTION: The floor of a class room measures 6m by 8m. The wslls are3m high and they contain four rectangular windows measuring 1.2m by 7cm. There is a door which measures 2m by 80cm. What p

Algebra ->  Test -> SOLUTION: The floor of a class room measures 6m by 8m. The wslls are3m high and they contain four rectangular windows measuring 1.2m by 7cm. There is a door which measures 2m by 80cm. What p      Log On


   

Question 1064293: The floor of a class room measures 6m by 8m. The wslls are3m high and they contain four rectangular windows measuring 1.2m by 7cm. There is a door which measures 2m by 80cm. What percentage of the total wall area is made up is taken up with windows and doors? Give your answer to 2 significant figures
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
The perimeter of the room is then,
P=2%28L%2BW%29=2%286%2B8%29=2%2814%29=28m
The total wall area is,
A=3P=3%2828%29=84m%5E2
Are the windows really 7 cm or did you mean 70cm. I'll do both.
The window area is,
A%5Bw1%5D=4%281.2%29%280.07%29=0.336m%5E2
A%5Bw2%5D=4%281.2%29%280.7%29=3.36m%5E2
The door area is,
A%5Bd%5D=2%2A0.8=1.6m%5E2
So then,
P%5B1%5D=%28A%5Bw1%5D%2BA%5Bw2%5D%29%2FA=%280.336%2B1.6%29%2F84=1.936%2F84=0.023 or 2.3%
P%5B2%5D=%28A%5Bw1%5D%2BA%5Bw2%5D%29%2FA=%283.36%2B1.6%29%2F84=4.96%2F84=0.059 or 5.9%