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The Consumer Price Index (CPI) measures the average prices of goods and services purchased by consumers. In the United States, the CPI-U calculates the CPI for all urban consumers.

　　The CPI-U is calculated based on prices of food, clothing, shelter, fuels, transportation fares, charges for doctors and dentists' services, drugs, and other goods and services that people buy for day-to-day living. All taxes directly associated with the purchase and use of items (such as, in the United States, sales taxes) are included in the index. An increase in CPI-U by a certain fractional amount means an increase by that fractional amount in overall prices within the relevant category.

　　For analyzing general price trends in the economy, seasonally adjusted prices are usually preferred over unadjusted prices because adjusting eliminates the effect of changes that normally occur at the same time and in about the same magnitude every year—such as price movements resulting from climatic conditions, production cycles, model changeovers, and holidays.



　　For each of the following, select Yes if the statement is inferable from the given information. Otherwise select No.

　　Percent Changes in CPI for All Urban Consumers (CPI-U), US City Average
Yes No
The changes in seasonally adjusted prices for used cars and trucks between March 2010 and September 2010 were in most cases less in magnitude than the changes in seasonally adjusted prices of new vehicles for the same period.
The seasonally adjusted CPI-U for all items was higher in March 2010 than in the previous month.
The seasonally unadjusted change in the price of new vehicles in August 2010 over the previous month was about the same as the seasonally unadjusted change in the price of food away from home over the same period.

The changes in seasonally adjusted prices for used cars and trucks between March 2010 and September 2010 were in most cases less in magnitude than the changes in seasonally adjusted prices of new vehicles for the same period.

Lets check the first question.
It talks about the seasonally adjusted values for used cars and trucks and those for new vehicles. So, we need to only look at 2 rows(new vehicles and used cars and trucks)and all columns between March 2010 and September 2010(7 months). We are asked whether the for the majority of months, seasonally adjusted values for old cars and trucks is lesser than those for new vehicles. Since it talks about majority, we need to tabulate or compare values till we get upto 4 yeses or nos. Let's quickly tabulate that

New Vehicles Used cars and trucks
March 2010 0.1 < 0.5 No
April 2010 0.0 < 0.2 No
May 2010 0.1 < 0.6 No
June 2010 0.1 < 0.9 No

Since, we have got four nos, we know that for the majority of months the answer is no. Since, we cannot infer the statement in question, the answer is no for this question.

2. The seasonally adjusted CPI-U for all items was higher in March 2010 than in the previous month.

This one asks us whether the seasonally adjusted values for all items in March 2010 was higher than Feb 2010. Now, we are not given the values for feb 2010. However, we know that at the top of the table it is mentioned that the Seasonally adjusted values given change from preceding month. Hence, the seasonally adjusted value for March 2010 is calculated from Feb 2010 and hence we just need to note whether the change for all items (the topmost row in the table) is positive for March 2010. It turns out it is(value=0.1). Since we can infer the statement in question, the answer is Yes.

3. The seasonally unadjusted change in the price of new vehicles in August 2010 over the previous month was about the same as the seasonally unadjusted change in the price of food away from home over the same period.

This one is tricky. It needs us to look for the seasonally unadjusted value which is the last column here. However, it wants us to compare the last column price change for new vehicles in august over preceding month with the last column price change of food away from home in the same period. We are not given this data and thus we cannot test the validity of this statement from the given data. Note here, we are not asked to confirm whether the data is right or not. We are asked to confirm whether the data can be inferred from the given data or not. Since, we cannot infer the data from the given information, the answer is no.

Let me know if this is clear or if you have any further doubts.


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Thanks
Kris
Instructor at Aspire4GMAT

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Press Kudos if this helps!

The thing that bothers me with question like the third one, is when they ask, "was about the same".

What qualifies as "about the same"? 10% 20%?

How should we approach the subjective and ambiguous term, "about the same"? Or something simliar like, " slighty more/less"?

I find this question to be especially annoying because of part 2:

2. The seasonally adjusted CPI-U for all items is higher in March 2010 than it is in the preceding month.

In the question, all items means "average", rather than "each of the items". This is clarified only by the existence of a separate table row with the name "All Items".

You need to stop and check every detail of the table to infer the meaning of all items, and I feel there is not enough time in the exam to do that.