SmarterEd

Aussie Maths & Science Teachers: Save your time with SmarterEd

Algebra, STD2 EQ-Bank 09 MC

The amount of paint (\(P\)) needed to cover a wall varies directly with the area (\(A\)) of the wall.

A painter uses 3.5 litres of paint to cover a wall with an area of 28 square metres.

How much paint is needed to cover a wall with an area of 42 square metres?

  1. 4.2 L
  2. 4.75 L
  3. 5.25 L
  4. 5.75 L
Show Answers Only

\(C\)

Show Worked Solution

\(P \propto A\)

\(P=kA\)

\(\text{When } P = 3.5 \text{ and } A = 28:\)

\(3.5\) \(=k \times 28\)
\(k\) \(=\dfrac{3.5}{28}\)
\(k\) \(=0.125\)

  
\(\text{When } A = 42:\)  

\(P\) \(=0.125\times 42\)
  \(=5.25\)

  
\(\Rightarrow C\)