Question 6

### Observation

The question was reported to attract majority of the candidates and they performed well in it.  Candidates were however, reported to have performed better in part (a) than in part (b).

In part (a), majority of the candidates were able to obtain the common difference,
d = 3 – 1  =  2.  They were also able to get the number of terms in the Arithmetic Progression by using the formula Tn = a + (n  -  1)d, where Tn  = 101, a = 1 and  = 2.  Substituting these values into the equation and simplifying gave n = 51.  The required sum was obtained by applying the formula  Sn =  (a + l), where Sn  =  Sum, n = number of terms  = 51, a = first term  =  1 and  l = last term  =  101.  This gave
Sn =  (1 + 101)  =  51 x 51  = 2601.

In part (b), it was reported that a few of the candidates were not able to draw a correct Venn diagram and this affected their ability to obtain the correct answer. Candidates were expected to represent the given information in a Venn diagram such as: