Tangible NCA - Borrowing Costs (Qn in BPP)

Dear Chris, I have difficulty understanding a question in BPP Kit - Tangible NCA: Leclerc Co has borrowed $2.4 million to finance the building of a factory. Construction is expected to take two years. The loan was drawn down on 1 January 20X9 and work began on 1 March 20X9. $1 million of the loan was not utilised until 1 July 20X9 so Leclerc was able to invest it until needed. Leclerc Co is paying 8% on the loan and can invest surplus funds at 6%. Calculate the borrowing costs to be capitalised for the year ended 31 December 20X9 in respect of this project. Borrowing costs (March – December) : $2.4m × 8% × 10 / 12 = 160,000 Investment income: $1m × 6% × 4/12 = 20,000 Ans: 140,000 The part that I do not understand is that - why do they only account 4 months of investment income? Since the question stated "$1 million of the loan was not utilised until 1 July 20X9 so Leclerc was able to invest it until needed", I thought that the investment is from 1 Jul - 31 Dec (6 months)? Or did I misinterpret the question? Thank you for your time! Hope to hear from you soon.