If you are talking about the 68-95-99.7 questions just dont even read the stuff it has for the solutions just kind of look at the graph it draws for you explaining it.. I pretty much just have that graph photographed in my brain and just think of it for all those questions..
On the other hand if you are talking about the ones like.. which has the biggest standard deviation it will give you choices like..
(8,10,12,14,16)
(24,26,28,30,32)
(40,42,44,46,48)
(1,3,3,5,7)
Then you dont have to do any actual math just look at the one that is different than the others.. The 1st three are all separated by just 2 points from the median/ mean, and then 2 points from that # (which means they all have the same standard deviation). The last one on the other hand has a completely different than the others and thus is the only 1 that could have a different SD so it is the answer..
And on the 3rd type of questions which actually deal with calculating the SD that is just a formula you have to know.