Question

John needs to paint a wall with spray paint. the wall has a diagonal of 43.6 feet and a height of 8.3 feet. if a spray can will cover 21.5 square feet, how many cans will john need?

Answer 1

Diagonal of a wall: d=43.6ft
Height of a wall: h=8.3ft
Length of a wall: l
d²=h²+l², l²=d²-h², l=√(d²-h²)
l=√(43.6²-8.3²), l=42.8ft
Area of a wall is: l*h=8.3*42.8=355.24ft²
One spray can can cover 21.5ft². 355.24/21.5=16.52
John will need 17 cans of spray.

Answer 2

The wall is a rectangle, so by the pythagorean theorem, the diagonal squared minus the height squared equals the width squared. This gives a width of 42.80 feet. The area of the wall is width (42.80 ft) x height (8.3 ft), equal to 355.26 square ft. The can covers 21.5 square feet, so John needs 16.52 cans to cover the wall. As he can't buy half a can, John should purchase 17 cans of spraypaint.The wall is a rectangle, so by the pythagorean theorem, the diagonal squared minus the height squared equals the width squared. This gives a width of 42.80 feet. The area of the wall is width (42.80 ft) x height (8.3 ft), equal to 355.26 square ft. The can covers 21.5 square feet, so John needs 16.52 cans to cover the wall. As he can't buy half a can, John should purchase 17 cans of spraypaint.