Answer:
[tex]4.36\text{ \% increase}[/tex]Explanation:
Here, we want to get the percentage increase or decrease in the number of units sold
Since the number of units sold in 2012 is greater than the number of units sold in 2011, we have an increase
Mathematically, we can have the percentage increase or decrease as follows:
[tex]\begin{gathered} \frac{Number\text{ of units sold in 2012 - Number of units sold in 2011}}{\text{Number of units in 2011}}\text{ = } \\ \frac{407-390}{390}\text{ }\times\text{ 100 \%} \\ \\ =\text{ }\frac{17}{390}\times\text{ 100 \% = 4.36\%} \end{gathered}[/tex]