As far as the years are concerned, there is a typing mistake which I will have corrected. The debentures should be convertible in 2010 – not 2020. Thank you for noticing.
As far as 10% is concerned, the only time I used 10% was as one of the ‘guesses’ for calculating the IRR, which is normal. The 7% is the growth rate in the market value of the shares and has been used correctly in both the lecture and the answer in the lecture notes.