Question

Ritchie wants to paint his bedroom ceiling and four walls.Both the ceiling and walls are 8 feet by 8 feet.A gallon of paint covers 40 squares feet.Which expression can be used to find the # of gallons of paint Ritchie needs to buy?

Answer 1

`\textrm{Number of gallons of paint required = }\frac{\textrm{Total Area Covered}}{\textrm{Area covered per gallon}}`

Explanation:

Each gallon of paint covers
`40`
`sq\textrm{ }ft` . All sides of the room as well as the wall are of
`8\textrm{ }ft\textrm{ }`×
`8\textrm{ }ft` dimensions.

So, clearly, the total paint covers all the walls and the roof. So, we can infer that
`\textrm{Total Area covered}=\textrm{ (Number of gallons of paint used) x}\textrm{ (Area covered per gallon)}`

`\textrm{Total Area covered = (4walls + 1 ceiling)\textrm{x}(Area of each wall)}`

`\textrm{Total Area covered = }8\textrm{ x }5\textrm{ x }5\textrm{ sq ft}`
`\textrm{ = }320\textrm{ sq ft }`

`\textrm{Number of gallons of paint required = }\frac{\textrm{Total Area Covered}}{\textrm{Area covered per gallon}}`
`\textrm{ = }\frac{320\textrm{ sq ft}}{40(sq ft)/(gallon)}\textrm{ = }8\textrm{ gallons}`

∴ Number of gallons of paint required =
`8\textrm{ gallons}`