GMAT Integrated Reasoning: Graphics Interpretation Example Problem #1

In June of 2012, the GMAT will contain a new 12 problem Integrated Reasoning section. To help you prepare for the IR section, we are working out the problems for you! Below is a sample IR Graphics Interpretation problem from the Graduate Management Admissions Council (GMAC) at www.mba.com.  You can find this and other integrated reasoning problems online at http://www.mba.com/the-gmat/nex-gen/integrated-reasoning-question-formats.aspx.

Solution:

Type of problem! Graphics interpretation

Tip! Your first step in analyzing graphics interpretation problems in the Integrated Reasoning section is always to examine and assess the data presented.

In this case, we have a chart spanning a time period that starts 4,600 million years ago and ends in the present (0 million years ago).  Note that the order of years is in ascending order from bottom to top; 4,600 million years ago (the oldest time period) is at the bottom of the chart on the left-hand side and 0 million years ago (the newest time period) is at the top.  Also look at the top of the chart, which tells you what data is being given for these million years: the chronometric eons, eon, era, period, and epoch.

Tip! On any chart, examine and understand your X & Y axis.

Confused about how the other two charts are related to the left-most chart? Read the text underneath the charts and you will find an explanation: each subsequent  column to the right shows the subdivisions of the timeframes to its left. Each of the rightmost two column groups is a magnification–with additional information–of a portion of the grouping directly to its left.  Note that they state this idea not once, but twice, so it must be critical to answering the questions.

Tip! Always read the text that follows the chart. It is there to help you understand the chart!

The middle chart is a magnification of the sky blue area called the “Phanerozoic Eon” in the chart on the left.  By looking at the top row, we see that the middle chart introduces new information, specifically the periods within the Phanerozoic Eon.  We also know from the left side of the middle chart that it is an expansion of a period within the left-most chart, specifically 600 million years ago to 0 million years ago.  In other words, the middle chart is providing additional detail to the chart on the left about a specific time period, 600 million years ago to 0 million years ago.

Likewise, the right-most chart is a magnification of a small portion of a Period listed in the middle chart in purple, the Tertiary Period.  By looking at the left side of the chart, we know this chart spans the period from 65 million years ago to 0 million years ago.  The top bar of the chart also introduces a new piece of information, the Epoch.

Remember, the right-most chart is a magnification of one portion of a period in the middle chart, which is a magnification of one portion of an eon in the left-most chart.

Now that we understand our chart, let’s take a look at our first question:

The question is asking about an epoch, the Miocene epoch, so our first step is to find the part of the chart with the label Epoch.

Tip! Always identify the specific chart or part of the chart that will help you answer the question.

We find epochs are only listed in the right-most chart.  Now we must find the Miocene epoch.  We see this towards the top of the chart, part of the Tertiary Neogene period.  The left side of the chart shows that the Miocene epoch lasted about 20 years, from approximately 24 million years ago to 5 million years ago.

The question is asking what percentage of an era the Miocene epoch spans.  Since there is no information about the era in the right-most chart, we must look to the left.  The middle chart gives us the information we need.  Remember, the right-most chart is a magnification of a small portion of the middle chart, the Tertiary Period.  We need to find the era during which the Tertiary period took place.  The middle chart shows that the Tertiary period (the period in purple) took place during the Cenozoic era (the light orange era).

Our final step is to figure out what percent of the Cenozoic era the Miocene epoch spanned.  There are two ways to go about this, a mathematical method and a logical method.

Mathematical Method:
For you right-brained folks, make a ratio of the number of years the Miocene epoch lasted to the number of years the Cenozoic era lasted and find the percent.  We already found that the Miocene epoch lasted approximately 20 million years.  By looking at the left side of the middle chart, we see that the Cenozoic era lasted approximately 70 million years.  We can boil this down to a simple ratio, 20/70, which equals about 35%.  Of the three choices we are given, 35% is closest to 25%.

Logical Method:
For those of you who hate numbers, there is also a way to logically deduce the answer without doing any math.  From the chart on the right, we know that the Miocene epoch took up nearly all (about 85%) of the Neogene period.  Eliminate 85% as an answer choice; it’s a trap for people who just look at the right-most chart.  From the chart in the middle, we know that the Neogene period took up about half of the Cenozoic era.  So we’re looking for an answer that is a little less than 50%.  Based on our remaining two answer choices, 25% and 3%, 25% is your correct answer.

Now that we’ve  correctly answered the first question, let’s move on to the next one.

The next question asks which of the following marks the beginning of a new eon, era, and period.  To answer this question, we must first find the chart that has all three pieces of information: eon, era, and period.  The only chart that lists eon, era, and period is the middle chart, so this is where you want to look for your answer.  Now let’s evaluate our answer choices.

Cambrian period: Based on the middle chart, the beginning of the Cambrian period (roughly 550 million years ago) also marks the beginning of a new era (the Paleozoic era) and a new eon (Phanerozoic eon).  This choice looks pretty good, but let’s evaluate all our choices before making our final selection.

Triassic period:  Based on the middle chart, the beginning of the Triassic period (roughly 245 million years ago) marks the  beginning of a new era (the Mesozoic era), but not a new eon (the Triassic period is still taking place during the Phanerozoic eon).  Eliminate this answer choice.

Pliocene epoch:  The pliocene epoch is not listed in the middle chart (it’s in the chart on the right) so it is probably incorrect, but let’s double check.  By looking at the chart on the right, we see that the beginning of the Pliocene epoch does not mark the beginning of a new period because it begins during the Neogene Period.  Eliminate this choice.

Precambrian eon:  The beginning of the Precambrian eon is also not listed in the middle chart (it’s in the chart on the left) so it is probably wrong, but we want to make sure.  Based on the left chart, the beginning of the Precambrian eon (approximately 4,600 million years ago) does not mark the beginning of a new era or period.  No eras or periods are listed on any of the charts until 500 million years ago.  Eliminate this answer.

Now that we have properly evaluated all our answer choices, we can confidently pick “Cambrian period” because it is the only choice that marks the beginning of a new period, era, eon.

Looking for Integrated Reasoning practice? Check out the links below!

Table Analysis Example Problem #1

Table Analysis Example Problem #2

Table Analysis Example Problem #3

Multi-Source Reasoning Example Problem #1

Multi-Source Reasoning Example Problem #2

Two-Part Analysis Example Problem #1

Two-Part Analysis Example Problem #2

Two-Part Analysis Example Problem #3

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5 Responses to GMAT Integrated Reasoning: Graphics Interpretation Example Problem #1

1. QUESTION says:

The answer to question 2 doesn’t make sense to me and I don’t understand how my interpretation of the chart (and question) can be wrong.

regarding the question… It states – “the beginning of the ____________ marks the onset of a new eon, era, and period in geological history.”

The word “BEGINNING” is crucial to my interpretation of this question.

I don’t understand how “cambrian period” can be correct when that period BEGAN during the Paleozoic Era. In truth the END of the “cambrian period” is what marks the BEGINNING of a new eon, era, and period.