The table summarizes information in several categories about the 9

Question

The table summarizes information in several categories about the 9 stores in a small grocery chain. The table also includes chain-wide averages where appropriate.

Store  
  Self-check
express lanes  
  Self-check
unlimited lanes  
  Pharmacy  
  Fuel  
  Restaurant  
  Average
customer age  
 
  A 
 8 
 4 
 yes 
 no 
 no 
 34.5 
 
  B 
 8 
 6 
 no 
 no 
 no 
 28.4 
 
  C 
 6 
 4 
 yes 
 no 
 yes 
 32 
 
  D 
 8 
 0 
 yes 
 no 
 no 
 50.5 
 
  E 
 12 
 4 
 yes 
 yes 
 no 
 42.5 
 
  F 
 8 
 6 
 no 
 no 
 yes 
 34.6 
 
  G 
 8 
 0 
 no 
 yes 
 no 
 38.8 
 
  H 
 4 
 8 
 yes 
 no 
 yes 
 29.9 
 
  I 
 0 
 0 
 yes 
 yes 
 yes 
 56.7 
 
   averages  
  6.89  
  3.56  
 - 
 - 
 - 
  38.66

For each of the following statements, select  True  if the statement can be verified to be true based on the information provided. Otherwise, select  False .

guddo · Accepted Answer

hi there, first sort the average customer age field. You will notice the trend that as age increases, the number of self check unlimited lanes decreases. Like any set of real world data, don't expect it to be perfect. One or two outlier points can be expected. However, do look at the overall/big picture. For the most part, the number of self check unlimited lanes decreases with increasing age. Also the difference in age from 28.4 to 29.4 is small so the two dots on a scatter plot would be relatively close together without skewing the overall trend.

souvik101990 · Answer

Yes I agree with  Nicoz .

I have also seen these problems in the GMAT again and again. The GMAT does not expect you to calculate the exact correlation coefficent or standard deviation as long as the trend is loud and clear. A few values may be here or there, but if there is an overall trend that is fairly spottable, you need to be able to identify it.

I remember a similar problems around standard deviation in my own GMAT take a few weeks ago where the question asked which one would have a higher standard deviation.

Sajjad1994 · Answer

Official Explanation

The last row in the "Self-check express lanes" column indicates that the average number of self-check express lanes per store is 6.89. The only two stores with average customer ages between 34 and 36 are Store A and Store F, each of which has 8 self-check express lanes—more than the average number, 6.89. So in each store with an average customer age between 34 and 36, the number of self-check express lanes is above average.

The correct answer is True.

Sorting the table by the "Average customer age" column, we see that stores with higher average customer ages generally tend to have fewer self-check unlimited lanes. Thus, the table shows a negative correlation between average customer age and the number of self-check unlimited lanes.

The correct answer is True.

Sorting the table by the "Self-check express lanes" column, we see that all three stores with less than the average number of self-check express lanes have restaurants, whereas only one store of the six with more than the average number of self-check express lanes has a restaurant. Thus, stores with fewer self-check express lanes than average are more likely to have restaurants than are stores with more self-check express lanes than average, not less likely.

The correct answer is False.

KarishmaB · Answer

In each store whose average customer age falls between 34 and 36, the number of self-check express lanes is above average. Sort by average customer age. Stores A and F are between 34 and 36. The number of self-check express lanes at both these stores is 8, which is higher than 6.89 (the average). Select True There is a negative correlation between the number of self-check unlimited lanes and the average customer age. The table is already sorted by customer age. Note the trend. The ages lower than average age have more number of self-check unlimited lanes (6s, 8s, 4s). The ages higher than average age have fewer lanes (0s and a 4). So the trend is clear. There is negative correlation. Correlation discussed here: https://youtu.be/Zx-PysHlhGM Select True Stores in this table that have fewer self-check express lanes than the chain-wide average are less likely to have restaurants than stores that have more self-check express lanes than the chain-wide average. Sort by 'number of self-check express lanes'. I, H and C have fewer than average. All 3 have restaurants so it is 100% probability. Many stores that have more self-check express lanes than the average have no restaurant. So their probability is certainly much lower. Select False

Apt0810 · Answer

1) In store A -average customer age = 34.5 ->SCEL-8(>6.89-average),Store F also has SCEL 8 ---True
2)True - Since SCUL increases and the Avg customer age decreases
3)False - I is the exception here

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RoughBook · Answer

2)True - Since SCUL increases and the Avg customer age decreases

Posted from my mobile device

Can someone please explain this. There are exceptions at 6, 8 and one of the fours if we arrange it according to ACA in ascending order.

bb · Answer

I agree. There is a negative correlation trend between age and SCUL (nice acronym) but there are exceptions, so I answered "no" as well... I will have to ask for help from someone with more IR experience as to why GMAC would classify this as "True"

Nicoz · Answer

It would be a negative correlation, so that’s true. In data analysis, one or two points can have different values means they are non-correlated but overall if you plot them and draw a line of correlation it would come out as negatively correlated with the function or factor compared.

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Posted from my mobile device

bb · Answer

Thanks! Now that you explain it, that makes sense.

but I did not like having a few values that were not fitting in the pattern....

unraveled · Answer

For the second question, we have increasing SCUL in the order 
      H=8 
      29.9

So for SCUL from 0 to 8, either ACA decreases from 56.7 to 29.9 or 50.5 to 29.9 or 38.8 to 29.9.
Hence a negative correlation. TRUE then.

r0g3rthat · Answer

I might be wrong in this approach, but if we take average of (average age values) for same no. of SCUL, it would certainly show a negative correlation.

SUCL - Avg(Avg Age)
0 - 48.5
4 - 36.33
6 - 31.5
8 - 29.9

This shows a negative correlation.

PS: I too marked it as a "False" in GMAT Prep.

Prakruti_Patil · Answer

This eGMAT article helped a lot in understanding corelation traps better: https://e-gmat.com/blogs/gmat-mastery-c ... ssentials/

I fell into the trap of considering inconsistencies too important to decide the trend!

samarpan.g28 · Answer

Hi  Akkiiii , let me help you. Negative correlation means if data in one column increases, then in other column to which we are correlating will decrease. If we sort the data in the column Self-check unlimited lanes, we will see that out of the total 9 values in the Average Customer Age column, 3 times it increases only and the rest 6 times it decreases from its previous cell. Additionally, the topmost and bottommost values in the Average Customer Age column suggest that the ages are sorted in descending order. Therefore, there is a negative correlation.

I hope it helps.

Arpitamitra · Answer

Can somebody help me understand Question 3.

chetan2u · Answer

Stores in this table that have fewer self-check express lanes than the chain-wide average are   less likely   to have restaurants than stores that have more self-check express lanes than the chain-wide average.

For checking the option, sort the table by  self-check express lanes .

I, H and C are below averages, but all three have YES in the retaurant column, so almost 100% likelihood.
On the other hand all othe rabove chain-wide average have NO in all excepy one case under Restaurant column.

SO, we can say that  Stores that have fewer self-check express lanes than the chain-wide average are  more likely  to have restaurants than stores that have more self-check express lanes than the chain-wide average.

Hence, not true.

egmat · Answer

I totally understand why the data might look scattered at first glance.   Key Insight:   negative correlation  does NOT mean a perfect downward line — it just means that, overall, as one variable increases, the other tends to decrease.

Let me sort the data by self-check unlimited lanes so the pattern becomes clear:

0  unlimited lanes: Store D ( 50.5 ), Store G ( 38.8 ), Store I ( 56.7 ) — average age around  48.7 
 4  unlimited lanes: Store A ( 34.5 ), Store C ( 32.0 ), Store E ( 42.5 ) — average age around  36.3 
 6  unlimited lanes: Store B ( 28.4 ), Store F ( 34.6 ) — average age around  31.5 
 8  unlimited lanes: Store H ( 29.9 ) — age  29.9

Now look at the group averages as unlimited lanes increase:  48.7  →  36.3  →  31.5  →  29.9 . That is a  clear downward trend!

Yes, there is scatter within each group — for example, at  0  lanes, ages range from  38.8  to  56.7 . But  correlation  measures the overall tendency, not perfection. Think of it this way: if you plotted all  9  points on a graph with unlimited lanes on the x-axis and age on the y-axis, the  best-fit line  would clearly slope downward. That is what makes it a  negative correlation .

The GMAT trick here  is that you do not need to calculate a  correlation coefficient . You just need to observe: stores with MORE unlimited lanes consistently tend to have LOWER average customer ages, and stores with FEWER unlimited lanes tend to have HIGHER ages. Every single store with  6  or  8  unlimited lanes has a below-average customer age (under  38.66 ), while every store with  0  unlimited lanes has an above-average or near-average customer age. That overall pattern is enough to confirm a  negative correlation .

Answer: True, True, False

INeel · Answer

Second part of the question 
out of 8 data points only 3 points show negative correlation this is below 50%. So how can we accurately describe it as a negative correlation. The relationship should at least be valid for 50% of the data points.

egmat · Answer

Hi INeel,

I can see exactly where this is coming from. Like samarpan's post above, you sorted by self-check unlimited lanes and then walked cell by cell down the age column, counting how many times age  drops  versus  rises . You found the drops don't clear a comfortable majority, so you concluded it can't be a negative correlation.

Here's the key fix:  correlation is not measured by counting consecutive point-to-point steps.  Correlation asks a bigger question -  as one variable goes up, does the other tend to go down overall?  A single jump the "wrong" way (or several) doesn't break it, and the count of up-steps vs. down-steps isn't the test at all. In fact, since several stores are  tied  on unlimited lanes ( three  stores at  0 ,  three  at  4 ,  two  at  6 ), your step-by-step count even depends on the arbitrary order you list the ties in - that alone tells you it's the wrong tool.

The reliable move is to group by lane count and look at the  average age  in each group. Using the table's real values:

-  0 lanes  (D, G, I):  50.5 ,  38.8 ,  56.7  - average  ≈ 48.7 
-  4 lanes  (A, C, E):  34.5 ,  32 ,  42.5  - average  ≈ 36.3 
-  6 lanes  (B, F):  28.4 ,  34.6  - average  ≈ 31.5 
-  8 lanes  (H):  29.9

As lanes go  0  →  4  →  6  →  8 , average age goes  48.7  →  36.3  →  31.5  →  29.9  - a clean, steady decline. That overall downward tendency is exactly what "negative correlation" means, so the answer is  True .

Quick rehearsal to lock it in.

Take x =  1 ,  2 ,  3 ,  4  with y =  20 ,  22 ,  10 ,  8 . Going  20  →  22  is a step  up  - a wrong-way move. But zoom out: high x sits with low y, low x with high y, and the best-fit line slopes clearly  downward . One wrong-way step doesn't override the overall trend. Same story here - don't let a couple of exceptions outvote the big picture.

Answer: True

The table summarizes information in several categories about the 9

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Store	Self-check express lanes	Self-check unlimited lanes	Pharmacy	Fuel	Restaurant	Average customer age
A	8	4	yes	no	no	34.5
B	8	6	no	no	no	28.4
C	6	4	yes	no	yes	32
D	8	0	yes	no	no	50.5
E	12	4	yes	yes	no	42.5
F	8	6	no	no	yes	34.6
G	8	0	no	yes	no	38.8
H	4	8	yes	no	yes	29.9
I	0	0	yes	yes	yes	56.7
averages	6.89	3.56	-	-	-	38.66

True	False
		In each store whose average customer age falls between 34 and 36, the number of self-check express lanes is above average.
		There is a negative correlation between the number of self-check unlimited lanes and the average customer age.
		Stores in this table that have fewer self-check express lanes than the chain-wide average are less likely to have restaurants than stores that have more self-check express lanes than the chain-wide average.

True	False	Statements
		In each store whose average customer age falls between 34 and 36, the number of self-check express lanes is above average.
		There is a negative correlation between the number of self-check unlimited lanes and the average customer age.
		Stores in this table that have fewer self-check express lanes than the chain-wide average are less likely to have restaurants than stores that have more self-check express lanes than the chain-wide average.

GMAT Graphs and Tables (G&T) Questions

The table summarizes information in several categories about the 9

Prep Toolkit

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

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My Rewards