Q1.2 BPP F5 Practice & Revision Kit (For exams up to June 2015)

Q1.2 When machine time is a binding constraint on production output, which one of the following will have NO EFFECT on the throughput accounting ratio for a product that the machine is used to manufacture ?
A Obtaining a lower purchase price for materials for the product
B Reducing factory costs
C Reducing the machine time per unit to make the product
D Increasing the selling price of the product

Answer is C.

I don’t think it’s correct because : reducing the machine time per unit will make throughput per unit of machine time higher and no effect to factory cost per unit of machine time , so TPAR will be higher.

How do you think about that ? BPP makes a lot of mistakes in their books lately