Question

To determine how much of each item to buy, tell whether you need to know area or perimeter. Explain your choice.

1. Wallpaper for a bedroom
2. Crown molding for a ceiling
3. Fencing for a yard
4. Paint for a basement floor

explain all answers and show work 

Answer 1

1. You need to know what area one roll of wallpaper will cover: length and width of roll. Then you need to know the area of the bedroom walls to be covered, making due allowance for doors and windows. Dividing the wall area by the area covered by one roll of wallpaper gives you the number of rolls you need to buy.
2. Amount of moulding around the ceiling depends on the perimeter.
3. Fencing is applied to the perimeter of the yard.
4. You need the area of the floor and you need to know the coverage details of the paint. Normally the recommended coverage is given on the tin of paint, for example, 1 litre covers a certain area measured in square metres.