I have just found the lecture is new on this topic and the answer on this example is different than the one that was for previous year. Could that old answer be accepted as well?
There are two ways of calculating planning and operational variances, which give different answers.
However the examiner always accepts either way.
(The previous examiner preferred one way, and all the study texts (and our lectures) therefore did it that way. The new examiner prefers the other way, and so all the study texts and revision kits (and our lectures) now do it this other way. The new way is in fact easier. However, again, the examiner will accept either method.)