Q 78 PM Kaplan Exam kit 2023-24

Hello Sir,

The model answer to this question telling that the fixed cost was not incremental but the question says Blunt is certain that the project will involve an incremental 500 labour hours.

This amount even the question is telling it is incremental but in the answer is telling not.

Can you please clarify

Thanks a lot.

Q
78 Blunt is considering a new project but is unsure how much overhead to include in the calculations to help him decide whether or not to proceed. Existing fixed overheads are absorbed at the rate of $8 per hour worked. Blunt is certain that the project will involve an incremental 500 labour hours.
The project will involve extra machine running costs and these variable overheads cost him $4 per hour. The number of extra machine hours is expected to be 450 hours. The difference between this figure and the 500 labour hours above is expected idle time.
The project will require a little more temporary space that can be rented at a fixed cost of $1,200 for the period of hire. This overhead is not included in the fixed overhead absorption rate above.

Answer
?
The relevant cash flow is:
510,300
51,300
511,600
Extra variable overheads: 450 hours >< $4/hr Rent
Total
51,800 51,200 53,000
Fixed costs are not incremental and idle time would normally mean that the machines are not in use are so are not an incurred cost.