Compute a weighted average forecast for the Week $6$ using a weight of $\mathrm{.}40$ for the most recent period, $\mathrm{.}30$ for the next most recent, $\mathrm{.}20$ for the next, and $\mathrm{.}10$ for the next.

Period $($t$)$Actual demand $($A$)$

Week $142$

Week $240$

Week $343$

Week $440$

Week $541$