e-GMAT Integrated Reasoning Articles

Hello all,

Here are few approaches that we think would be applicable to this particular question. Please pick best approach as per you, and why you think so.

Approach 1 - Computational Approach

Current Mean = Sum of all 13 data/13 = 185/13=14.23;
New Mean = (Sum of all 13 data + 5+19)/15 = 209/15= 13.53;
Mean decreases instead of increasing. Answer is NO.

Approach 2 - Smart Computational Approach

To get the value of current mean, we need to sum all 13 datasets, an approach that is time consuming.
Let’s make some observations. Observe Lawn Tennis column when arranged in ascending order.



There are 9 data points- 4, 6, 8…..20 as highlighted in red color. These data points form a series with equal interval. So their sum is equal to middle-most value*9= 12*9= 108.
Now, Current Mean = Sum of all 13 data points/13 = (Sum of all 9 data points + 18+19+20+20)/13 = (108+77)/13=185/13=14.23;
New Mean = (Sum of all 13 data points + 5+19)/15 = 209/15= 13.53;
Mean decreases rather than increasing. Answer is NO.

Approach 3 - Logical computational approach

Calculation of current mean is done in same manner as is done in approach 2.

We find that current mean is 14.23, which is greater than the mean (12) of Manish and Imran [(5+19)/2=12].
What will be the new mean of after inclusion of Manish and Imran?

Mean fundamental

Mean of a dataset cannot be less than the least value (Here it is ‘12’) and more than the highest value (Here it is ’14.23’). It will lie in between (do not read- Mid value). This implies that the new mean after inclusion of Manish and Imran will be less than 14.23.
So mean decreases rather than increases.

Approach 4 - Logical approach

Mean of 2 new values added= (5+19)/2=12
Current Mean of 13 data points is not known.

We need to deduce whether the new mean increases ?

New mean > Current mean, only and only if current mean < 12 (Mean of the 2 new values). Because if current mean > 12, the lower value 12 will pull the current mean towards it, and in that scenario, new mean will be less than the current mean

So we need to find whether the current mean < 12 or not?

Say current mean = x.

To answer the question, we need to know if the current mean increases by at least 2 points or not when the two data points are included?

So Is New mean > x+2?

We can form a mathematical equation as below



There are 13 data points & 2 new inclusions - so total 15 data points for new mean

Upon solving, we get x ≤ -3. This means to get an increment of 2 over the current mean, current mean has to be at the max. -3.
Well, -3 is an absurd value since the mean of given data set cannot be this value.

Mean fundamental

Mean of a dataset cannot less than the least value (Here it is ‘4’- Karren’s score), and more than highest value (Here it is ‘20’- Stacey’s score). So the answer is NO.

Approach 5 - Inference approach

Inference through New mean

For new mean to absorb an increment of minimum 2 points over the current mean, the current mean has to be much less than 12, because after an increment of 2 or more points, new mean MUST be less than 12.

Let’s observe what could be the probable value of current mean?



Let’s look at the Lawn tennis column. From Karren till Joe, there are total 8 data points. Their mean would be equal to median, because they have an equal interval of 2 points successively.
Now, the median of these 8 data points is 11 [(10+12)/2]. So mean would also be equal to 11. Rest of the data points are much higher than 11, so current mean would be more than 11. We already concluded earlier that new mean MUST be less than 12. If current mean is more than 11, then after an increment of 2, it can never be less than 12. So the answer is NO.

Hope this helps build your fundamentals. Do attempt challenging MSR question posted today.

-Shalabh
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It’s been 6+ months since the launch of Integrated Reasoning section. With scores from 105K+exams, GMAC has enough data to conduct some preliminary analysis to evaluate the value that Integrated Reasoning section adds. Read below for some key takeaways from the reports.


Key takeaways:

1. The correlation of IR with GMAT Total is .55. In other words, Quant, Verbal, and IR are all measuring something related, yet also different.
2. IR score is important because, other things being equal, the test takers demonstrating more skill in this area within each range can be expected to be better students.
3. 85% of current students and alumni find IR skills to be very relevant and useful in the work place. Similarly, nearly all (97%) of the employers surveyed said the skills—such as the ability to integrate, organize, combine, and synthesize information—were important.
4. IR and Admissions: The biggest value is that IR is an additional data point. It assesses information that we don't currently capture in the admissions process. I think it is going to make our process more complete. We're going to be able to make better decisions because we have that additional set of data that is so relevant to what students are going to do in the MBA curriculum, but also in their careers – Quote from Tuck.





e-GMAT has launched the world’s most comprehensive IR course that contains 35+ concepts, 120+ original questions, and 2 full length IR mock tests. The course allows an average GMAT test taker to master the section in less than 12 hours. Click hereto know more.


[youtube]https://www.youtube.com/watch?v=cr_jC5BD99c[/youtube]

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Till I read this announcement, I was of the same opinion as Sachin and Carcass. However, the findings of this report surprised me (were some sort of an eye opener too). Traditionally, GMAT has served two purposes:

1. It has been taken as a predictor of the student's performance in B-school.
2. It is a symbol of prestige. Schools flaunt their mean and median GMAT scores as a proxy for prestige/selectivity.

Having completed an MBA, I can vouch that the skills tested on the GMAT IR are at least as relevant for B-School (and post B-school) success as the skills tested in the quant and verbal section. The IR skills are probably more important in schools such as Stern, Duke etc. (finance focused schools). The trend with big data will make these skills important again in fields such as Marketing.

Why are GMAC's findings interesting?

Lets understand GMAC's findings. The stats have proven that regardless of your GMAT score, the IR score has a distribution. This probably means that even those who score 750, a good percentage of them (half of them if you go by the stats) do not score well on the IR. Considering that the skills tested on IR are important to academic and professional success, I believe that it is possible that schools will start considering them seriously.

Lets fast forward a few months and go to September'2014 - the year when the first batch that was tested on IR completes their first year. I bet that schools will start taking IR more seriously if GMAC can prove that there is a much higher likelihood that a student with a GMAT score of 650 and with an IR score of 7 or higher is likely to perform better than one with a GMAT score of 700 and an IR score of 6 or lower (Remember IR has low correlation with Quant and Verbal Scores).

So yes, IR may not be as important right now, but it could be very important in a year from now.

-Rajat
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Really interesting stuff. Thank you for posting, Rajat!

I definitely believed that schools wouldn't care about the IR section for at least another three or four years, but maybe the validity studies will prove IR's value far earlier than I thought. I actually agree that the IR section seems to test more important skills than the rest of the GMAT (data interpretation is far more valuable than number properties or modifier placement, right?), but I figured that b-schools already have plenty of data points on applicants, and the IR data point is unlikely to say anything terribly new about any given candidate.

And it looks like I'll be very wrong about that. Rajat, you're completely correct: if the next batch of studies proves that somebody with a 700 composite and a 5 on the IR performs worse in b-school than a student with a 700 composite and a 7 or 8 on IR, the game will change really quickly.

For whatever it's worth, I'm a little bit skeptical of this first batch of data. Despite GMAC's best marketing efforts, many test-takers aren't taking IR seriously yet, and some well-prepared test-takers (including many of our friends in this forum) are likely to conserve energy on IR, and therefore get a lower IR score relative to their quant and verbal scores. Maybe it's not a large effect, but I wouldn't be surprised if the correlation figures are skewed by the fact that many test-takers refuse to take the IR seriously yet. My bet is that the correlation between IR and quant/verbal scores will slowly inch upward, but not nearly enough to invalidate the IR section.

It will be really interesting to see what happens when GMAC has more complete data over the next year or two. Despite my mild skepticism about this first batch of data, it looks like GMAC is well on its way to proving that the IR section matters, and soon it will just be a question of how long it will take for adcoms to fully embrace the data.
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Dear Charles,

Your hypothesis is quite likely. It was difficult for me to fathom that a large # of folks who did well on the Quant and Verbal sections did not do as well on IR. I do believe that the correlation between quant and verbal scores and IR score will increase as well.

On the other hand, one could argue that GMAC may make IR questions more challenging to ensure that a high enough correlation is maintained. Moreover, as schools start considering IR scores, more and more people will take it seriously. Whatever be the case, the next 12 months will be interesting.

-Rajat
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Hi fameatop / Egmat ,

Could you please explain this equation below ( how did you derive it ) ?


This means that the combined score of 2 new students must be equal to ->
= [Current Mean score (excluding 2 new students) X No of new students] + [Required Increase in Mean score x No of current students]
= [Min 10 x 2] + [ Min 2 x 13]
= Min 20 + Min 26
= Min 46

Hi 1991sehwag,

We know that Sum of all the numbers in the set = Mean of the set * No. of numbers in the set
So before the addition of two new students in the class, we had

Total combined score = 14.23 * 13 = 185.

Once two new students are added the mean score increases by at least 2 points and the number of students also increases by 2. Hence we can write

Total minimum new combined score = (14.23 + 2 ) * 15 = 243

The increase in the combined score is because of the addition of the scores of the two new students. Hence their combined score should be minimum of 243 - 185 = 58. Since the statement tells us that their combined scores was ( 19 +5 ) = 24, the statement is not true.

Hope this helps

Regards
Harsh
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