Anonymous Wrote:From the question, Let I1 > I2, I3 where I1 is the most expensive item and I1 and I2 be the least expensive ones.
After, 20% off on I1 and 10% off on I2, I3, their prices reduce to .8I1, .9I2 and .9I3 respectively
Now converting the wording in the question to mathematical expression we need to find - >
.2I1 + .10I2 + .10I3 > .15(I1 + I2 +i3)
solving, we get I1 > I2 + I3 ( This is actually the question......we need to determine)
1) I1 =50 and I2 or I3 = 20, therefore if I2 or I3 =20 (the 2nd expensive one), the least expensive cannot be more than 20
so A answers the question...as YES
2) is insufficient as it only tells about one number.
perfect.
this problem is also a classic C TRAP.
a
c trap is a problem that's clearly written to be difficult, but on which both statements taken together are VERY CLEARLY sufficient.
and by VERY CLEARLY i don't mean "after i solve
this equation, and move
that over
there, then ... oh yeah, my memorized rule of thumb tells me they're sufficient" - i mean it's OBVIOUS. (examples follow, for those of you who have your og's handy.)
on these problems, you can rest assured that (c) is not the answer. also, because the two statements together
are sufficient, you can also strike answer (e).
this leaves only (a), (b), (d). and in the dream situation, in which one of the answers by itself is clearly insufficient, then you can guess that the other one must be sufficient - and you'll be right a startlingly high percentage of the time.
you should NOT use the "c trap" approach as a PRIMARY method - i'm sure that, one fine day, a difficult "c trap" problem will come along to which the answer actually
is 'c' (although i've yet to see one) - but, rather, as an AID TO GUESSING.
still, if you get into a guessing situation, the c trap is one of the strongest weapons in your arsenal.
this problem:
*
identify the problem as a c trap: if you take the two statements together, then you have the prices of ALL the items in the problem. if that's the case, then the answer to the prompt question is clearly either "yes" or "no"; hence, sufficient.
kill (c) and (e) and narrow the choices to (a), (b), and (d).
* statement (2) is insufficient. this isn't ridiculously obvious, but the presence of two remaining unknowns should convince you (remember that you're in guessing mode here).
kill (b) and (d).
answer = a.