Diluted EPS in Sep.16 Triage question

Hello. I have noticed the difference in calculation of diluted EPS by ACCA examiners and by all learning providers.

This is the extract from Triage question:

The following notes are relevant:
(i) Triage Co issued 400,000 $100 6% convertible loan notes on 1 April 20X5. Interest is payable annually in arrears on 31 March each year. The loans can be converted to equity shares on the basis of 20 shares for each $100 loan note on 31 March 20X8 or redeemed at par for cash on the same date. An equivalent loan without the conversion rights would have required an interest rate of 8%.
The present value of $1 receivable at the end of each year, based on discount rates of 6% and 8%, are:

End of year
6% ————-8%
1)0·94——-0·93
2)0·89——0·86
3)0·84——0·79

Tax rate -20%

This is where the difference lies:

1) Percentage used for finding saved interest (extra earnings). Open Tuition (in the example 2 of chapter 19) and BPP use simple interest rate, while Kaplan and ACCA (in this example) use an effective interest rate.

Obviously, you may say that in the example 2 of OT, an effective interest rate is not mentioned, so use whatever rate is given. However, this creates confusion. Because when I see a similar problem, I automatically discard effective interest rate and use simple rate, since this is the way I see in your lectures and text.

2) The basis figure for calculating saved interest (extra earnings)

ACCA examiner splits convertible note into a debt component and equity component. So 40000 is divided into 37792 (debt) and 2208 (equity). Then the examiner finds saved interest by multiplying debt component by effective interest rate and after tax %

37792 x 8% x (1-0.2)=2418.

This is not the way how all learning providers teach. If I follow the way taught by learning providers I would calculate saved interest as follows:

40000 x 8% (or 6% depending on the book I read) x (1-0.2).

So I ask you to clarify this matter. What is the correct percentage rate? What figure should be taken as a basis figure?