Hi, there. I'm happy to help with this. The first statement
:The changes in the seasonally adjusted prices for transportation services between March 2010 and September 2010 were, on average, less than the changes in seasonally adjusted prices of energy services for the same period
Well let's look at those two. For the transportation row, we have:
0.4, 0.4, 0.4, 0, 0, 0.4, 0.3
What exactly do those numbers mean? Well, the prompt tells us:An increase in CPI-U by a certain fractional amount means an increase by that fractional amount in overall prices within the relevant category
That's not very well worded at all. What's the source of this question? Reading that line in the prompt, I would think that it's trying to say --- a 0.4 is a 40% increase in price. That's fine, but I notice some of the values in the table are negative numbers less than one, like -1.6, but you can't have a drop in price of more than 100%!!! So, I am going to guess that means, 0.40 is a forty-cent increase, and -1.6 is a $1.60 decreases --- either that or something similarly additive --- but if that's what they mean, it's far from perfectly clear in the wording.
We'll take that latter interpretation as the our tentative working model.
One thing that's tricky is --- the first number in the sequence, 0.4 for transportation and 1.4 for energy, is the change in CPU-I from the previous month
(February 2010) to March 2010, so if we considering the change from March to September, we don't include that first number
For transportation, that gives us 0.4 + 0.4 + 0 + 0 + 0.4 + 0.3 = 1.5 --- I guess that's a $1.50 increase in CPU-I from March to September.
For energy, we have (-0.5) + (-0.5) + (-1.6) + 0.9 + 0.8 = -0.9 -- so, energy had a net drop in the period from March to September.
Again, the unclear wording has me feeling like I am guessing at exactly what they mean, but if I have guessed correct on my interpretation, then the numbers indicate that transportation increased more than energy --- in fact, transportation increased, and energy decreased, from March to September. So, the answer to the first question is No
. The second statement
:The seasonally adjusted price for used cars and trucks was higher in September 2010 than it was in March 2010.
Scanning across the "used cars and trucks" row, we see all positive numbers except a (-0.7) at the end --- that would cancel out the +0.7 immediately before it, and the sum of the others would have to be positive. A net positive change from March to September. Therefore, the September value is higher --- the answer is Yes
Does all this make sense?
Here's a free lesson about GMAT IR:http://gmat.magoosh.com/lessons/644-int ... -reasoning
and, in case you haven't see it already, here's a free eBook about the IR question:http://magoosh.com/gmat/2012/gmat-integ ... ing-ebook/
I hope all this is helpful. Please let me know if you have any additional questions.
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