Cash management exam

I need help too, have my resit in November!

Same chapter - same rubbish
Calculate the interest on 6.4% Treasury stock 20x4 with a current market price of $116.
The answer they give is 5.52%.

What do I miss in this task?

Thank you a lot.
If it is possible, where did you get this formula. There is no common logic - thats for sure.So far.

@genesta have you looked back over your revision/text books??

work out what needs to be received in period 4 and 5:
Period 4 = 30% of period 3 CREDIT purchases, plus 70% period 2 CREDIT purchases, plus period 4 CASH purchases

Any sales made by cash are paid IN the period of sale.

Received in period 4:
Period 3 sales = (8800*£30) = £264000
£264000 * 85% = £224400
£224400 * 30% = £67320
(the 85% is the amount of sales on credit. You do not need to included the 15% cash sales as this has already been received in the period). (the 30% is the amount of sales to be received in period 4).

Period 2 sales = 8500*£30 = £255000
£255000 * 85% = £216750
£216750 * 70% = £151725

Period 4 CASH sales will be received in that period:
6100*£30 = £183000
£183000 * 15% = £27450

Total period 4 = £67320+£151725+£27450 = £246495

Hope you can work out the same for period 5