Dusty Company (Sept/Dec 19)

I have three queries regarding the problem I’m having in question Dusty Co (Sept/Dec 2019)

[Problem 1]
(a)(i) requirement asked to calculate current inventory management system:

Each current order is 1,500,000/12 = 125,000 units per order
Average inventory = 125,000/2 = 62,500 units

Purchase Price = (62,500 x $14) = $875,000
Finance cost = $875,000 x 0.03 = $26,250

Since the Current Total Inventory cost is $16,149 but here examiner didn’t add the finance cost of $26,250 in the calculation of total inventory (why not?)

[Problem 2]
(a)(ii) requirement asked to calculate Inventory cost under EOQ model:

What is the correct way of calculating the holding cost either we should add the holding cost per unit in EOQ formula or not?

a) EOQ without Finance cost = (2 x 252 x 1,500,000/0·21)0·5 = 60,000 units/order
or
b) EOQ with Finance cost = (2 x 252 x 1,500,000/0·63)0·5 = 34,641 units/order

Which one is correct (a) or (b)?

[Problem 3]
There is a tutor’s note in the examier’s answer which says that:-
“It would also have been acceptable to revise the holding costs in (ii) and (iii) to reflect the finance cost of holding inventory (e.g. $0·63 in (ii)) and this approach could be awarded full credit if correct”

I know that finance cost should be added BUT where it should be added is my question that we should add the finance cost per unit in EOQ formula OR we should add finance cost when we calculate cost of holding to calculate total inventory costs (i.e. Order cost + Holding cost)