30. At the end of september, the combined share price of ardent stock and biofirm stock exceeded the share price of Compuwin stock by approximately
31. During which of the following months did the aggregate share price of stock in all three companies change the LEAST?
I'm happy to help.
First of all, here's a free IR ebook you may find helpful:http://magoosh.com/gmat/2012/gmat-integ ... ing-ebook/
One important skill on IR is estimation --- see:http://magoosh.com/gmat/2012/the-power- ... mat-quant/Question #1
At the end of September:
Biofirm is just less than 50 --- we could say 49 or 50
Argent is about 15
Compuwin is about 33
Notice --- exact values are not as important, because we are going to estimate.
B + A is about 65 --- that's essentially double what C is. If thing #1 is double thing #2, then thing #1 is 100% greater than thing #2. Therefore, (A + B) are about 100% greater than C. Answer = (D)Question #2
Let's look for some low-hanging fruit here ----(A) July
- hmmm B has a big jump, and A & C have little drops, hmmm(B) August
- hmmm, this looks promising, because C stays level, the the rise in B seems equal to the drop in A(C) October
- NO WAY -- huge drops in B & C, only a modest rise in A(D) November
- the drop in C seems equivalent to the rise in A, but B also rises --- a net gain --- NO WAY(E) December
- NO WAY - gigantic rise in A and small rise in C are no way offset by small drop in B.
Without any calculations, with purely visual inspection, I can see that (C)
are out. Now, I have to look more careful at (A)
. In (A) July
, the gains in A & C are small, even combined --- it seems the rise in B is enough for a net gain. Meanwhile, in (B) August
, the the rise in B seems equal to the drop in A, and C stays flat, so that really looks like zero change.
Answer = (B)
Are you familiar with the phrase, "A picture is worth a thousand words
"? That's the principle of a graph --- that's why mathematicians & data wonks love graphs. We can convey so much information visual, and one of the big ideas of working with graphs on the GMAT is not to get sucked into numerical calculations each time, but to process the graphs visually
Does all this make sense?