information given... 12 undergrads - 3 weeks...

So 1 undergrad 36 weeks
and the que asks about how long it will take 8 grds?
So u basically need info that will relate undergrads to grads..

lets go to ans choices...

1. just what we need... undergrads to grad ratio is 3/5
no need to calculate... u can get how long it will take for 1 grad to complete and hence how long 8 grads will take... Suff

2. looking at this.. it will give u an equation between grads and undergrads, also the information provided will give another equation.. 2 eq and 2 unknown...gud enuf.... Suff

Ans D.

There is no need to calculate ans in DS... unless it is absolutely necessary.. and if u r calculating... then just check that...both the choices i.e. 1 & 2 gives u the same and only one answer...
If u have some other strategy solving DS...do follow that and dont follow what i have suggested.....