Borrowing costs

Hello Sir. I am struggling with a question.

L has borrowed $ 2.4 million to finance the building of a factory. Construction is expected to take 2 years. The loan was drawn down and incurred on 1 January 20×9 and work began on 1 march 20×9. $1 million was not utilised until 1 july 20×9 so L was able to invest it until needed. L 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 Dec 20×9 in respect of this project.

What i understood is we have to capitalise for 10 months which makes 10/12* 8% * $2.4 m which is $ 0.16 m. and also deduct investment income for the months L used the loan. i am having an issue with the months here. Do i have to take from 1 january to 1 july? it then makes 5/12*6%* $1m which makes $0.025m

And finally getting a net answer of 135 000$. In the revision kit it says for the investment income we should take only 4 months into consideration.
Please Sir, could you explain the difference?