Get Approximate Date from Week Number - powershell

Question

I'm getting information on monitors from WMI. There are properties called "WeekOfManufacture" and "YearOfManufacture". In this case it's:
Week : 24
Year : 2009
I'm trying to get the approximate date corresponding to that.
I'm doing this to get a really rough estimate:
(Get-Date -Date $YearOfManufacture/01/01).AddDays(7*$WeekOfManufacture)
But obviously the "week" doesn't necessarily always have 7 days.
What is the best approach?
The complete code I'm using right now is:
$Monitors = Get-WmiObject WmiMonitorID -Namespace root\wmi
foreach ($Monitor in $Monitors) {
$Manufacturer = ($Monitor.ManufacturerName -notmatch 0 | ForEach{[char]$_}) -join ""
$Code = ($Monitor.ProductCodeID -notmatch 0 | ForEach{[char]$_}) -join ""
$Name = ($Monitor.UserFriendlyName -notmatch 0 | ForEach{[char]$_}) -join ""
$Serial = ($Monitor.SerialNumberID -notmatch 0 | ForEach{[char]$_}) -join ""
$WeekOfManufacture = $Monitor.WeekOfManufacture
$YearOfManufacture = $Monitor.YearOfManufacture
$DateManufacture = (get-date -Date $YearOfManufacture/01/01).AddDays(7*$WeekOfManufacture)
"$Manufacturer - $Code - $Name - $Serial - $DateManufacture"
}
which returns something like (info obfuscated):
SAM - 1234 - SycMastr - XXXX - 06/18/2009 00:00:00
SAM - 1234 - SycMastr - XXXX - 09/10/2009 00:00:00

Answer 1

Answer from Technet works perfectly
(https://social.technet.microsoft.com/Forums/en-US/f65c80b0-f74f-4234-870c-c5ffe8d9b1ea/powershell-get-date-from-week-number-of-year?forum=ITCG)
:
Function FirstDateOfWeek
{
param([int]$year, [int]$weekOfYear)
$jan1 = [DateTime]"$year-01-01"
$daysOffset = ([DayOfWeek]::Thursday - $jan1.DayOfWeek)
$firstThursday = $jan1.AddDays($daysOffset)
$calendar = ([CultureInfo]::CurrentCulture).Calendar;
$firstWeek = $calendar.GetWeekOfYear($firstThursday, [System.Globalization.CalendarWeekRule]::FirstFourDayWeek, [DayOfWeek]::Monday)
$weekNum = $weekOfYear
if($firstweek -le 1) { $weekNum -= 1 }
$result = $firstThursday.AddDays($weekNum * 7)
return $result.AddDays(-3)
}
FirstDateOfWeek -year 2009 -weekOfYear 24
8 juin 2009 00:00:00