Observation

This question was reported to be very popular among the candidates. Majority of them attempted it and they performed very well in it.
In part((a), candidates were reported to show that the sixth term of an Arithmetic Progression (A.P.) is
a + 5d = 37…………….…(1)  and using the sum of the first six terms as 147 to get
2a + 5d = 49………………(2).
Solving the simultaneous equations, the first term is 12 and common difference is 5
In part (b), they went on by substituting for the first term (a) which is 12 and common difference (d) which is 5 into the general formula for sum of an Arithmetic Series to obtain S15 = {2(12) + (15 – 1)5} = 705.