The question was a very popular one as it attracted almost all the candidates. 
Most candidates who attempted the question had  very good presentations and excellent calculation.  The candidates correctly calculated the data in the demand schedule.  They were handsomely rewarded with high marks.

However, a few weak candidates  performed poorly in the calibration of the axes as the intervals were inconsistent, leading to poor shapes of resultant demand curves even when graph sheets were used.  These shortcomings amounted to loss of substantial marks.

However, the overall candidates’ performance was well above average.

The very good candidates presented their answers in the format below

(a) When q is 2, P = 20 – (2 x 2) = 20 – 4 = 16 Dollars.
When q is 3, P = 20 – (2 x 3) = 20 – 6 = 14 Dollars.
          When q is 4, P = 20 – (2 x 4) = 20 – 8 = 12 Dollars.
          When q is 5, P = 20 – (2 x 5) = 20 – 10 = 10 Dollars.
          When q is 6, P = 20 – (2 x 6) = 20 – 12 = 8 Dollars.
          When q is 8, P = 20 – (2 x 8) = 20 – 16 = 4 Dollars.

         
(b)    Price
                                                                       
           

                                                                                             Demand function: P = 20 – 2q

                        
       O                                                                            Quantity

(c)      The lower the price, the higher the quantity demanded and the higher the price the lower the quantity demanded, other things being equal.