Few Questions that were asked to me via PM. I am responding here so that everyone can benefit.
1) Where to study Mean/Median/SD problems ?
I didn't really do anything extra for these topics. Usual review from KAP, Princeton is enuf I feel. To get good problems on these, use the forum and search topics on these. Few Things to remember:
a) Mean of an equally spaced sequence is (first Number + Last Number)/2
b) Mean = Median for equally spaced sequence.
c) More often than not in order to compare SD of two sequences, u wud
need to know all the numbers in the sequences
d) SD = 0 and range = 0 for a sequence where all numbers are the same
or for a sequence where there is only one number.
e) A sequence with closely spaced numbers has lesser SD than a
sequence which has larger variation in numbers.
f) SD for different sequences will be the same if they all are equally
spaced e.g. SD for 2,4,6 (diff of 2) will be the same as 16,18,20
(diff of 2)
2) 8 principles of SCs:
These are nothing different than what is listed in all the books KAP, Princeton and KAP800. However, I found that inordinate number of GMAT SCs test ||ism e.g. when you see
not only XYZ.....make sure u immediately focus on a choice which has
but also XYZ and not
but also TBZ. Word matching in ||ism helps a lot to quickly ans questions. I think 80% of the OG expl are based on ||ism. Therefore, I wud recommend to always be on lookout for || structures in choices.