In this homework we model the Quarterly Amazon Revenue $($million dollars$)$ starting in

Quarter $3$ of $2014$ and going through Quarter $4$ of $2019.$ In Quarter $4$ of $2019,$ the Amazon Revenue was $87,437$

million dollars. Use the output provided in the homework material to find the updated forecast for the Amazon

Sales for Quarter $1$ of $2020.$ With the homework output we include the estimated model accounting for a linear

trend and the seasonality. we also include the estimated AR$(1)$ model.

The variable time period is coded in the following way: Start with t $=1$ for Quarter $3$ of $2014,$ t $=2$ for

Quarter $4$ of $2014$ etc. The value of t will increase by $1$ for each subsequent quarter. In this example we created

indicator variables for quarters $1,2$ and $3.$ Here quarter $4$ is the baselevel.

$1.$ Find the value of t $($time period$)$ for Quarter $4$ of $2019.$