Under over absorption

Isn’t it true that you need to know The Amount of the overhead that has been absorbed and the actual amount to ascertain whether an overhead has been under or over absorbed.

In this Acca practice question

A company uses absorption costing with a predetermined hourly fixed overhead rate. The following situations arose last year. Would each of these situations cause overheads to be under absorbed or over absorbed? .

Actual overhead expenditure was less than the budgeted expenditure

Actual hours worked were less than the budgeted hours used to set the predetermined overhead absorption rate

….

The first one is ok, but I’m having problems with the second one. The answer is under absorbed. But we don’t know the actual expenditure, so how can we say the overhead is under absorbed.