$1.($Forecasting$)$ Weekly demand for a product is given in the table below:

$($a$)$ Using Microsoft Excel, plot the weekly demands, and comment on it by considering the components of a time series.

$($b$)$ Apply the $5-$week moving average method to make forecasts for weeks $6$ through $10.$

$($c$)$ Take the estimated value of the level at the end of week $5$ as the moving average value computed in part $($b$)$ for week $5.$ Choose $\backslash (\backslash$alpha$=0\mathrm{.}2\backslash ).$ Apply the method of simple exponential smoothing to determine single$-$week$-$ahead forecasts for demands $6$ through $10.$

$($d$)$ Choose $\backslash (\backslash$alpha$=0\mathrm{.}2\backslash )$ and $\backslash (\backslash$beta$=0\mathrm{.}3\backslash )$ and apply the method of double exponential smoothing to determine single$-$demand$-$ahead forecasts for demands $6$ through $10.$

$($e$)$ Using Microsoft Excel, on the same graph, plot the forecast errors of the methods in parts $($b$),($c$),$ and $($d$).$ Do you observe any bias in the methods in parts $($b$),($c$),$ and $($d$)?$ Show your answer by any method of measuring bias.