Overhead absorption rate

A company has established the following budgeted fixed overheads for the forthcoming period:

…………………………. £’000 ……… Bases of apportionment
Heating and Lighting … 12 …………….. Cubic capacity ……
Welfare costs …………. 7 ………….. Number of employees
Power ………………….. 42 ……………….. Kwh usage ……..
…………………………… –– ………………………………………..
………………………… Total 61
…………………………… –– ………………………………………..

Other information:

…………………………… Department 1 .. Department 2 .. Maintenance … Total
Cubic capacity (m3) ……… 6,000 ………… 7,500 ………….. 2,500 ……. 16,000
Employees (number) ………. 20 …………….. 30 ………………. 6 ………….. 56 ..
Power
(kwh usage) ………………. 35,000 ………. 25,000 …………………………. 60,000
Labour hours ……………… 28,000 ………. 48,500 …………………………. 76,500
Machine hours ……………. 40,000 ………. 39,000 …………………………. 79,000

The maintenance department splits its time between Department 1 and Department 2 on a ratio of 2:3.

The management accountant has partially completed an allocation and apportionment statement:

…………………. Department 1 .. Department 2 …. Maintenance
……………………….. £ ………………… £ ……………….. £ …….
Heat and Light ….. 4,500 …………… 5,625 ………….. 1,875 …
Welfare …………… 2,500 …………………………………………….
Power ……………. 24,500 …………………………………………….
……………………. ––––––– ……………………………………………
………………… Total 31,500 ………………………………………….
……………………. ––––––– ……………………………………………

What would be the overhead absorption rate in Department 1 (to 3 decimal places)?
A £0·788/machine hour
B £0·814/machine hour
C £1·125/labour hour
D £1·163/labour hour

The answer is B but I can’t see where this has come from; e.g. 31,500/40,000 machine hours would give A…