The graph shows monthly temperature data, in degrees Celsius (°C),

Question

3.jpg The graph shows monthly temperature data, in degrees Celsius (°C), about the Earth’s troposphere as measured by Satellite X. It presents the mean for the month less the mean for the entire 8-year period. The graph also includes a line of best fit for the data points shown. For each of the following, use the drop-down menu to create the most accurate statement on the basis of the information provided. To evaluate the conclusion that Earth’s mean tropospheric temperature declined over the 8-year period shown, it would be most helpful to see a more comprehensive graph of the same period of time that showed GRAPH_1_PLACEHOLDER The conclusion that Earth’s mean tropospheric temperature declined over the 8-year period shown would be most weakened if the set of measurements in GRAPH_2_PLACEHOLDER were revised toward the current line of best fit.

Apt0810 · Answer

1)D, Here first three options won't work since broadening of horizontal or vertical axis by any parameters will not at that much extra detail,since that would only Increase the granularity of the data,but in order to confirm/reach a conclusion we need to have tropospherical readings from other satellites ,which can confirm the baove findings validity

2)D, If we revise the data of 2008 and bring it above the line of best fit then the decline conclusion will not work through

Posted from my mobile device

2)D, If we revise the data of 2008 and bring it above the line of best fit then the decline conclusion will not work through

Posted from my mobile device

mSKR · Answer

1. the conclusion can be made more specifically if we have readings of all months and years for the given time frame .we have already these readings.

how to validate?
in order to confirm we need to check these readings from other satellites as well
A: we have already
B: it doesnt help as we have still rough numbers from graph and conclusion is determined
C: we are concerned about temperature readings
D is better

2.2008 readings are lower and thus reduced the overall mean temperature.
so any change in 2008 would be greatest among other years.
D

Sajjad1994 · Answer

Official Explanation

Taken by itself, the graph and its line of best fit support the conclusion that Earth’s mean tropospheric temperature declined over the 8-year period shown. Given that the data are already plotted monthly, adding labels for months to the axis would not change the data plotted in the graph. Since none of the data points stray beyond the currently plotted area on the vertical axis, there is no clear reason to broaden the range of that axis, and, even if it were broadened, the trend shown in the graph would remain the same. Given that mean tropospheric temperature is the only characteristic in question, additional characteristics are not likely to have any effect on the trend shown in the graph. However, if tropospheric temperature readings from other satellites were very similar to those shown in the graph, the conclusion drawn on the basis of the graph would be strengthened, and if those other readings were instead different from those shown in the graph, the conclusion could be weakened.

The correct answer is tropospheric temperature readings from other satellites.

For a revision of data points toward the line of best fit to weaken the conclusion that Earth’s mean tropospheric temperature declined over the 8-year period, it would have to result in some of the lowest temperatures toward the latter part of the 8 years being revised upward or some of the highest temperatures in the earlier years being revised downward. This would lessen the negative slope or result in a positive slope of the line of best fit. Since the low temperatures in 2008 are significantly further from the best-fit line than the highest temperatures in 2001, the greatest increase in slope in the best-fit line would result from revising temperatures in 2008 toward the current best-fit line.

The correct answer is 2008.

AlphaCentauri4ly · Answer

AndrewN  Absolutely flummoxed! I had no idea where to begin or how to interpret the graph. I'm not even sure if I'm seeing English alphabets anymore. And what does "It presents the mean for the month less the mean for the entire 8-year period" even mean?

AndrewN · Answer

Hello,  AlphaCentauri4ly . I will admit that I had no idea what you were talking about until I had already completed the two questions. I looked at the graph, knew what a line of best fit represented, and jumped straight into the questions. I consider information that explains a graph to be there on a need-to-know basis. In this case, you do not need to know that information to answer either question, and the confusing verbiage would only slow your pace and increase any feelings of anxiety you might be experiencing. My advice? Stop worrying about qualifying every bit of information upfront. Just lean on the question and answer choices for hints. There are a few key pieces of information that can get you through both questions:

The   blue   line of best fit has a negative slope, so the average value (of whatever the y-axis says—the numbers clearly decrease from top to bottom) is decreasing   The first question mentions the  tropospheric temperature  declining over 8 years, corroborating the information in the title and on the x-axis

That is it. With a little logic, I whittled down the answer pool to the first question, and then I repeated the process for the second. Who cares about the blurb under the graph if it does not help you answer the questions? Simplify your approach.

By the way, if you are reading this,   Sajjad1994  , I like to pitch in whenever I think sharing my thoughts might be helpful. I am rarely called in to weigh in on an IR question, but I am happy to do so. I appreciate the encouragement.

- Andrew

MrChalo · Answer

for the second part of the question, they are asking you to check if the values from the year (2001, 2004, 2007, 2008) has a negative slope or not?
i am not understanding the explanations above.

For me the best answer was 2007 because if i check the values there they are all over the mean of the 8 years, so if i only saw those i could say that the mean was not getting lower by each year because if the 7th year had all its months over the mean maybe it was getting hotter each year.

Apk641 · Answer

PART 1

What Would Help:

If other satellites provided similar temperature data, it would strengthen the conclusion, because it would indicate that the readings from this satellite (Satellite X) are accurate and consistent with other measurements.
Conversely, if other satellite data differed, it would weaken the conclusion, casting doubt on whether the trend shown in the graph is a true representation of the Earth's tropospheric temperature.

PART 2

Looking at the Graph:
The graph shows mean deviations of tropospheric temperature over time (from 2001 to 2009), with each point representing the deviation from the 8-year mean for each month. There is a line of best fit showing a slight downward trend, suggesting that the Earth's mean tropospheric temperature declined over this period.

Why 2008 Is Key:
In 2008, there are several data points that are significantly below the mean (around -0.3°C or lower), which indicates cooler-than-average temperatures for that year. This drop in temperature pulls the overall trend downward, contributing to the conclusion that the Earth's mean tropospheric temperature declined over the 8-year period.

Why Revising 2008 Weakens the Conclusion:

If the data for 2008 were revised upward (closer to or above the mean), the overall downward trend would be less pronounced. This would weaken the conclusion that there was a decline in the Earth's tropospheric temperature over the 8 years, since one of the coldest years would no longer appear as a significant anomaly.

Why 2001 Is Less Important:

Looking at the graph, the data points for 2001 fluctuate around the mean, with no extreme deviations like we see in 2008. The values in 2001 appear to be fairly close to zero, meaning that year doesn't contribute much to the overall downward trend. Revising the data from 2001 wouldn't significantly affect the overall conclusion about the decline in temperature because the points are already near the average.

Sebastian55 · Answer

For those struggling with the second question like me,

The word revised is used to call into question. Say you were to call into question 2007, where the temperatures are above the mean, maybe they'd be a little lower ok but that still doesn't have a big impact as in "the average/slope wouldn't change much".

Now if the 2008 points were to be revised, maybe the data points weren't as steep as they are... best case scenario they the dots would be closer to the mean and the negative slope wouldn't be as steep.

KarishmaB · Answer

Responding to a pm:

Read the y axis - small +, 0 , - values. It represents the difference between the mean and the monthly readings. The average of all 8 periods was calculated and was found to be say X. In some months readings were above X (positive, higher than 8 year avg temp) and in some months it was below (negative, lower than avg temp).Overall trend is downward as shown.

1. To evaluate the conclusion that Earth’s mean tropospheric temperature declined over the 8-year period shown, it would be most helpful to see a more comprehensive graph of the same period of time that showed ____ 
  
 - months and years on X axis - the data of months and years is already given on X axis 
- broader range on vertical axis - the data lies within the range given so broader range will be useless
- additional characteristics - we are concluding about temp only. Additional characteristics are not useful
- Readings from other satellites - Satellite X gives a single measurement every month. Its error may not be averaged out. Multiple measurements by other satellites will improve data accuracy (the way a study is conducted multiple times over different samples to improve accuracy) so this will be useful

Select "Readings from other satellites"

2. The conclusion that Earth’s mean tropospheric temperature declined over the 8-year period shown would be most weakened if the set of measurements in _____ were revised toward the current line of best fit.

We see that the trend line is downward. What will weaken the conclusion that the temp is declining? Something that straightens out the trend line or reverses the trend.

2001 - If 2001 readings (   between    2001 and 2002 on the graph) move toward the trend line i.e. upwards, the  trend  line will fit even better in the downward slope since initial year will have higher temperature.   
  2004 - If 2004 readings move upward, the decline in temperature trend may look a bit more abrupt toward the end but it will likely be downward only.   
 2007 - If 2007 readings move down (toward the trend line), the trend line will fit even better to its current position.  
 2008 - If 2008 readings move up toward the trend line (put your finger on the current 2008 readings (between 2008 and 2009) and assume they are clustered on the trend line) then would the trend line even slope down? Then if we were to draw the trend line, we would likely draw a flat line since the years have ups and downs. The 2008 readings are the ones which seem to be pulling the trend line down. It they were to move up, the trend line will flatten out.

Select "2008"

Goldenfuture · Answer

trick after 45 mins of spending time on this lil friend. If we zoom in a graph a tiny change loooks more - if we zoom out a loine looks flatter. And zooming in makes it looks steeper.

For the last one - check deviation from trend line - the more one is - that's your answer.

Adit_ · Answer

Bunuel   KarishmaB

The first part, if there were additional factors involved the argument gets weakened and if no additional factors were involved the current argument holds. I understand that having other tropological satellites also does the same but I felt additional factors would make or break the graph entirely. What was wrong with that?

Considering every year there are so many factors involved, now these temperatures could either reflect all those changes, through which we can conclusively say like yeah they decreased or these factors werent taken into account then the argument weakens as its not a comprehensive temperature plotting.

Bunuel · Answer

What’s wrong is that “additional characteristics” is too vague and not directly tied to checking the key vulnerability in the conclusion. After all, we are concerned about the temperature only. “Additional factors” could mean anything. Some of those are causes, some are irrelevant, and none automatically tells you whether Satellite X’s temperature series is accurate. That’s why it’s not the best choice here.

The conclusion is based on one satellite’s measurements. The most direct way to evaluate whether the apparent decline is real is to see whether independent instruments measuring the same thing show the same pattern. “Readings from other satellites” targets that exactly.

Adit_ · Answer

I did briefly think along those lines however the wording said "comprehensive" and anything comprehensive I thought would include every factor across all dimensions involved making it thus conclusive and comprehensive. If simply other satellites give more readings it only makes it more conclusive but not comprehensive as would additional factors right?
I'm sorry if I am diving too deep I just want to clarify since my thinking was pretty much along the same lines as well.

Bunuel · Answer

Yes, I think you’re overcomplicating it. The “other satellites” option is a cleaner fit than “additional characteristics,” because “additional characteristics” is too vague and could be irrelevant, so it’s simply not as strong.

The graph shows monthly temperature data, in degrees Celsius (°C),

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Graphs and Tables (G&T) Questions

The graph shows monthly temperature data, in degrees Celsius (°C),

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards