$1)$ Using the cost equation $($Y$=$a$+$bX$)$ you obtained from the regression analysis in Step $1,$ plug in Quarter $21\text{'}$s COGS into the equation and estimate the NI$.$ Compare the estimated NI to the actua NI

$2)$Add an indicator variable "Covid" to your regression analysis. Let Covid$=0$ for quarters ending before March, $2020,$ and $1$ otherwise. Rerun your regression analysis. Attach your regression output and interpret it $($R$-$square, coefficients, t$-$stat, p$-$value, etc.$).$

$3)$ Using the cost equation $($Y$=$a$+$bX$+$Covid$)$ you obtained from the regression analysis in Step $3,$ plug in Quarter $21\text{'}$s COGS into the equation and estimate the NI$.$ Compare the estimated NI to the actual NI$.$ Compare the estimation precision and reliability in Step $2$&$3$ with those in Step $1.$ Explain steps on how to donon excel or provide spreadsheet