reapportion

7a.26 The following question is taken from the January to June 2016 exam period.
An accountant is using the repeated distribution method to reapportion service department costs. The
following table shows the work she has done so far. Figures that are yet to be calculated are shown as
“???”
Production Production Service Service
department department department department
1 2 X Y
$ $ $ $
Apportioned and allocated
Production overheads 60,000 80,000 20,000 10,000
Service department X 8,000 10,000 –20,000 2,000
Service department Y 7,200 4,200 600 –12,000
Service department X ??? ??? –600
Total production overhead ??? ??? 0
What is the total production overhead for production department 1 after the remaining reapportionment
of the overheads of service department X?
? $74,600
? $75,200
? $75,440
? $75,467

the answer: By examining the second row of figures in the table it is clear that service department X’s costs
are reapportioned on a 40% , 50% , 10%. On the final reapportionment no overhead is
reapportioned to service department Y, so the balance of overhead should be reapportioned
40/90 and 50/90. This results in the following total production overhead for production
department 1. ($60,000 + $8,000 + $7,200) + 40/90 x $600 = $75,467

can u please explain me why are they taking 40\90 and not 100