Weekly IPhones Sales (In $1,000s)in an Apple Store for the Past

Essay

Weekly iPhones sales (in $1,000s)in an Apple store for the past three months are shown in the table below.Compute the four-week centered moving averages.
$$\begin{array} { | c | c c |} \hline \text { Manth } & \text { Week } & \text { Sales } \\\hline 1 & 1 & 14 \\& 2 & 22 \\& 3 & 20 \\& 4 & 16 \\\hline 2 & 1 & 18 \\& 2 & 20 \\& 3 & 24 \\& 4 & 20 \\\hline 3 & 1 & 22 \\& 2 & 26 \\& 3 & 24 \\& 4 & 18 \\\hline\end{array}$$