Remember that we can get the mean of a dataset by adding up each datum and dividing such sum by the number of data.
Now, let's call the number of puppets Marco made M
This way, we would have that:
[tex]\frac{1+4+3+M}{4}=3[/tex]
Solving for M :
[tex]\begin{gathered} \frac{1+4+3+M}{4}=3 \\ \\ \rightarrow\frac{8+M}{4}=3 \\ \\ \rightarrow8+M=12\rightarrow M=12-8 \\ \Rightarrow M=4 \end{gathered}[/tex]
Therefore, we can conclude that Marco made 4 puppets.
