The report also stated that although majority of the candidates attempted part (a) of the question and performed well in it, it was observed that majority of them converted first to base ten, solved it and converted back to base 2.  Very few candidates were reported to have worked in base 2.  1112 = 112 = 101012. 
110002 – 101012 = 112. 

In part (b), majority of the candidates were reported to have found the question quite challenging.  They were expected to show that if p is the cost price of a television set, then the total sales for 18 sets = 115 x 18p = 20.7p.  Similarly, total 100 sales for 2 sets = 95/100 x 2p = 1.9p.  Therefore total sales on the 20 sets x 20.7p + 1.9p = 22.6p.  Total cost price  on the 20 sets = 20p.  Hence, percentage profit
=  22.6p – 20p    x  100  =  13%.
        20p                   1