The data shown below is used to forecast the sales for week $5$ with the exponential smoothing model.

Week

$1$

$2$

$3$

$4$

Sales

$165$

$140$

$115$

$200$

Forecast

$170$

$168$

$140\mathrm{.}1$

The smoothing factor $($alpha$)$ should be:$\_\_\_\_\_\_\_\_\_$

Question $1$ options:

Not enough information is given to determine the smoothing factor

$0\mathrm{.}5$

$0\mathrm{.}3$

$0\mathrm{.}4$