Weighted average

first you need to summerize your table to bring the QTY and FACTOR inline 

go to Modeling at the top of the page and then select new table.

in the formula bar enter the code below 

Calculated_Table = SUMMARIZE('Table', 'Table'[Entity],"QTY" , Sum('Table'[Quantity]),"FACTOR",sum('Table'[Factor])  )

adjust for your actual table names and colunm names 

this will output your table with the values inline

EntityQTYFACTOR

add a calculated colunm for the wighted

Column = Calculated_Table[QTY]*Calculated_Table[FACTOR]

then create a measure to dum these and devide by sum of qty

Measure = DIVIDE(sum(Calculated_Table[Column]),sum(Calculated_Table[QTY]))

final out put