Data Insights Ep. 3: Key Quant Skills for Graphical Interpretation

[@joyfulcancer003]

for the last question, Average = Total Value of transaction / Number of transaction . We are told Total Value increased by 11/10 and from the graph total number decreased by (2/22=1/11) to 10/11. so fraction changes by (11/10 * 11/10) = 121/100 . total increase of 21%.

[@adityarai35]

Can you please explain

[@samirjereissati1]

what a great surprise find gmat ninja. Amazing methodology,very practical and cover all GMAT FOCUS curriculum. Thank you guys for doing this for providing this for us. I bought Manhattan Prep and I'm regret, bcs there is neither explanations nor strategy on how to approach questions.

[@GMATNinjaTutoring]

Thank you for the kind words! I'm glad that the videos are helping a bit. Enjoy, and have fun studying!

[@ariyanakhan1816]

GMAT Ninja is a lifesaver, thank you so much guys!!

[@GMATNinjaTutoring]

Thank you for watching! ❤️

[@sharmamukul19]

Thank You, Alex and Charles, for this much-needed wonderful series.

[@GMATNinjaTutoring]

Thank you for the comment -- so glad you found the video helpful!

[@ashishsinha9035]

Thanks GMAT Ninja and Alex for the wonderful session ! My regards to Mr. Charles. I was able to solve 3/4 questions correctly, including the last one.

[@GMATNinjaTutoring]

Thank you so much for all of the positive comments! I'm glad that you're enjoying the videos. Have fun studying, and keep us posted on your progress! - Charles

[@himakshibatra]

I took 100 and 110 as total values for T6 and T9. Those gave me A9 as 110/20 and A6 as 100/22 --> A9/A6 gave me 121/100.

[@Catnidhi]

Excellent session! Would appreciate a similar series for verbal!

[@GMATNinjaTutoring]

Hi there! We've got similar series for verbal. Check out our reading comprehension series here: kzbin.info/aero/PLiaK8zyGGndlDghCtnUwhbPUU1qyJKcj0 And our critical reasoning series is here: kzbin.info/aero/PLiaK8zyGGndkmDpY6c99ESXreEbr_EILp I hope that helps!

[@TanishqUpadhayay-m8z]

Thank you so much for this series, really needed this. 🙏

[@GMATNinjaTutoring]

Thank you for checking out our videos -- glad you're finding the series helpful!

[@ashwinkumarnair4104]

Thank you GMAT Ninja for the wonderful explanation. I have a question: When you give 30 seconds, what aspects of the question should I focus on? I can only interpret the graph but can't really make sense of the text in 30 seconds. Are there better ways to read it in 30 seconds?

[@GMATNinjaTutoring]

Good question! Generally speaking, reading the text below the graph will be an essential investment before tackling the questions. The goal is to read carefully and grasp the big picture of what's being presented, without trying to memorize all the details (you can always go back if you need to for these). Instead of limiting yourself to 30 seconds for the graph plus text, I'd start by going through this process without worrying about time, making sure you're reading precisely. As you get more comfortable with this process, and more familiar with these questions, you'll hopefully get more efficient. From another angle -- people tend to lose time on Data Insights because of rushing and missing key details, so training yourself to read precisely is often the key to efficiency. I hope that helps!

[@Anu22059]

Great video, I love how you simplify all the scary looking terms into something easy to process. Thanks for the work you do

[@GMATNinjaTutoring]

Thanks for checking out the video -- glad you found it helpful!

[@KadizAkther]

Thanks for uploading

[@tanmaytrillion9694]

Thank you sir, well explained. I Learned each concept from this awesome series

[@GMATNinjaTutoring]

Thank you so much, and have fun studying!

[@DamiAbegunde]

That last question is criminal

[@shanicesegolenemaatchideku770]

I just sat there like a dog in front of a TV. 😅

[@BarrySwami10]

Do you mean was it hard or easy? Genuine question.

[@saajidify]

Need to be carefull, the term value and number are two different.

[@Yaaha_Maaja_Ayega]

Gmat thinks we are the grandson of Einstein to solve such lengthy questions under 2 mins😂

[@niri_fc]

No, he just explained it in a complicated way. Just assume the total transaction values of all credit card transactions (I assumed 220 million for 2009 and 200 million for 2006 - consistent with the 10% increase data) and dividing by the total number of transactions to figure out the change in average yielded 21%

[@ashishsinha9035]

Thanks for the fantastic video. I have one doubt though.Had the first question of the first graph (in the present video) asked the median of points earned, what would have been the answer?

[@GMATNinjaTutoring]

You wouldn't be asked about the median number of points earned from this graph because the graph just isn't set up for that question. It's possible to ask about the median in terms of a range, but it's not possible to tell precisely which point is the median. This means we can say the median is somewhere between 800 and 850 points, but we can't say for sure what it is exactly. I hope that helps!

[@user-uh3lg7mw8e]

Thank you so much for this video!I'm taking a GMAT Focus test soon, so I bought an OG (2023-2024), but it doesn't have any practice questions for Data Insights. Do you have any idea where I can practice DI like practice questions or mock tests?

[@GMATNinjaTutoring]

Good question! The paper and e-book OG's will have Data Sufficiency questions (which are on Data Insights). However they will NOT have any Graphical Interpretation, Two-Part Analysis, Multi-source Reasoning, or Table Analysis questions. For those you'll need to look at the online question banks. If you bought the OG already, I believe you should be able to access an online question bank with all those Data Insights questions. Other sources of Data Insights questions include: 1) The OG Data Insights Review Online Question Bank. 2) Data Insights Official Practice Questions 1 and 2, Online Question Banks. 3) The official practice tests (though I would absolutely save those for the end of your review process, when you're comfortable with the test as a whole, and ready to take full practice exams, to simulate the real test). Let me know if that helps at all!

[@user-uh3lg7mw8e]

@@GMATNinjaTutoring Thank you so much for the detailed answer! I bought the OG and panicked there were no questions for the four parts you wrote 😂. I was aware of no.1 & no.3, but is no.2 the same as no.1? I thought these weren't enough tbh😂. I'm nervous since there aren't many mock tests or exam reviews even though I'm pretty good at math and IR. Thank you!!

[@aishwaryapriya9416]

​@@user-uh3lg7mw8e From where to access the resource mentioned in point 1

[@GrantBreneman-yi5yo]

Really excited for this series! Will there be a data insights test taking strategy episode? If so, when could we expect it to be released?

[@GMATNinjaTutoring]

Thank you for the kind words, Grant! We have a "video 0" planned for the Data Insights series, similar to our quant intro video that covers general approaches for the section. We'll probably release the Data Insights overview video after we've completed the rest of the series -- that way, "video 0" can address concerns that viewers raise on the rest of the videos. That said... well, the GMAT Focus Edition will be operational starting November 7, so we'll try to make sure that the overview video is ready before that. Have fun studying, and feel free to reach out anytime if you have questions!

[@vijaykarena3388]

Thank you so much Man- Tonnes of love from India.❣❣💯

[@ExpertSupport-hd9qd]

The last question can be solved easily avoiding algebra Let say, The value of credit card transaction in 2006 is $22 million. Then, the value of credit card transaction in 2009 will be = $22 million*1.10= $24.2 million. So, Average Value in 2006= $22 million/22 million =$1 Average value in 2009 = $24.2 million/20 million = $1.21 Percent Change = $1.21/$1.00 = 21% Is that OK? Please

[@GMATNinjaTutoring]

Yes -- that is a great way to do it! In some questions, picking a number and plugging it in can lead to ugly calculations. But in this case, picking $22 million for the total value of the 2006 credit card transactions makes the solution straightforward. Thank you for this comment!

[@AmanSaxena5]

So, Average Value in 2006= $22 million/22 million =$1 Average value in 2009 = $24.2 million/20 million = $1.2 How did you get this average value 22 and 20 for 2006 and 2009 respectively?

[@sankalpabhishek8018]

Hi, is there an easier logical approach or some quicker method apart from such detailed algebra for last question last part, esp due to time paucity on DI questions, would be really helpful, Thanks

[@GMATNinjaTutoring]

Good question! Yeah, for this question, it's possible to work through it fairly quickly as follows: 1) Recognize that Total Value = Average Value x Number of Transactions --> V = AT 2) Define the variables as follows --> T9 = Total Value in 2009, A9 = Average Value in 2009, etc. 3) Produce the following equation: (20)(A9) = (11/10)(20)(A6) 4) Solve for A9 --> A9 = (1.21)(A6) --> So A9 is 21% greater than A6 Thanks for the question, and let me know if that helps at all!

[@pennypeng5785]

Hello team, a question regarding fish sold and fertilizer problem. Q1 asks about the average amount decreased from year 1 to year 5, and the blank follows by dollars, why is that the slope of decrease? I was calculating the average dollar amount between these two years. Thanks!

[@GMATNinjaTutoring]

As you point out, it's useful to look at the units for the answer they're asking for. Looking at the blank in this case, we see it's followed by the phrase "dollars per 10kg of apples per year." What does that mean in math terms? Well, "per" means divide. The y-axis already tells us "dollars per 10 kg of apples sold," so we'd need to divide that by years (i.e. "per year"). So we can't just find the average of two different y-values on the graph -- that wouldn't incorporate the important words "per year." But how do we incorporate years into our calculation? Well, note that the question is asking for the average decrease in the price of apples per 10kg per year, from year 1 to year 5. It can be helpful to know that "average change" on a graph is referring to the slope -- you might say that's a piece of math content that's useful to know. Also, note that if we calculate slope, it will give us the proper units (dollars per kg per year). Thanks for the question, and let me know if that helps at all!

[@rodrigobernal-c4r]

In rates of change Q2, the apple farm and fish pond exercise, it says "after year 3 the rate of growth per year was..." -> shouldn't I look at year 2? And compare the rate of years 2 and 3? What happens if in year 2 it was decreasing and then year 3 the slope is positive. Its weird to me to compare it with year 4. Can you expand? Thanks! :)

[@GMATNinjaTutoring]

That's a great question! Let's take close look at the wording: "After year 3, the rate of growth in the total number of fish sold per year was....." Let's break down this question into it's components. First, it's asking about the "rate of growth in the total number of fish sold per year." That tells me I'm looking at the dotted line, and I'm thinking about the "rate of growth," i.e. the slope of the line. But what time period are they asking about? Well, they want to know about "After year 3." At that point, I think the simplest interpretation would be that "after year 3" means the part of the graph "after" year three. That is, starting at year three and continuing to the end of the graph. Since the slope starts steep and gets less steep "after" year three, the rate of growth is decreasing. Thanks for the question, and let me know if that helps at all!

[@rodrigobernal-c4r]

@@GMATNinjaTutoring Thanks! It really helps me to be more precise about the language.

[@sancharighosh2817]

In the fish and fertilizer question, how is the growth decreasing? The rate was slower from Y4 to Y5 but wasn't it still increasing? Can you please explain in details?

[@GMATNinjaTutoring]

Great question! As you say, the number of fish sold per year is increasing from Y4 to Y5. BUT, the question is not asking about the number fish sold per year; rather, it's asking about the RATE OF GROWTH in the number of fish sold per year. So what does that mean? What's the RATE OF GROWTH in the number of fish sold per year? Well, the rate of growth is basically the slope of the line. The rate of growth from Y3 to Y4 (i.e. the slope from Y3 to Y4) is 1000/1 = 1000. The rate of growth from Y4 to Y5 is 500/1 = 500. Now, what is happening to the RATE OF GROWTH after year 3? Well, from Y3 to Y4 it's 1000. But from Y4 to Y5 it's only 500. So the rate itself decreased by 500. Yes, the rate from Y4 to Y5 is still positive (500). But the rate from Y4 to Y5 is 500 lower than it was from Y3 to Y4. Thus the rate of growth is decreasing. Let me know if that helps at all!

[@sancharighosh2817]

Understood, thanks! Also, in case it was reversed, I mean if the rate was initially slower from Y3 to Y4 and then started increasing steeply from Y4 to Y5, what would have been the answer then?@@GMATNinjaTutoring

[@amanjagtap]

at 29:10 why did you minus 0.05 from 0.005? please explain

[@GMATNinjaTutoring]

Good question! The goal at that point in the video is to calculate the slope between two points. More specifically, we want to find the slope between the first point on the blue line and the last point on the blue line: (1, 0.05) and (5, 0.005). The slope formula is (Y2 - Y1)/(X2 - X1). Plugging the two points in into the formula, we get (0.005 - 0.05)/(5 -1) = -0.045/4, which is around -0.01. Thanks for the question, and let me know if that helps!

[@2minutesbusiness597]

In the question related to Test audiences starting somewhere in 21:00 minutes. How should we co-relate? For example, Here D is going down and F is going up so it is negatively correlated, but why D here is taken as primary parameter? What if we say F is going up when D is going down. Shouldn't it be positively corelated?

[@GMATNinjaTutoring]

When we're thinking about correlation, it doesn't matter which we define as the 'primary' parameter and which is defined as the 'secondary' parameter. We can interchange the parameter we define as the 'primary' parameter and the correlation will remain the same. If the value of parameter B increases as the value of parameter A increases, then parameters A and B are positively correlated. We can reverse this and say that if the value of parameter A increases as the value of parameter B increases, then parameters A and B are still positively correlated. If the value of parameter B decreases as the value of parameter A increases, then parameters A and B are negatively correlated. We can also reverse this to say that if the value of parameter A increases as the value of parameter B decreases, then parameters A and B are still negatively correlated. I hope that helps!

[@valentinzhurba8230]

for the last problem 1.1/(20/22)=1.21... that is total value becomes 110% and it's divided by decreased number of transactions (20/22)... just understand that during the test there won't be 10-15 minutes to write all these derivations... moreover, they are unnecessary

[@adityarai35]

HOW did you rule out 3.5 and 2.5 in the first question?

[@GMATNinjaTutoring]

Good question! To find a median, you need to order your data points from low to high, then select the one that's in the middle. If you have 5 data points, the median will be the third data point. For example, if I had the data points 1,5,6,8,10, then 6 would be the median. If you have an even number of data points, on the other hand, the median value will be the average of the middle two data points. For example, if I had the data points 1,5,6,8, the median would be (5 + 6)/2 = 5.5. In this question, we are given a total of 33 data points (i.e. we have data for 33 total students). Using the logic above, we can conclude that the median will be the 17th value if they are listed from low to high. Additionally, note that the time data are all integers (i.e. 1 hour, 2 hours, 3 hours, etc.). Therefore, we know that the median must also be an integer, since it will equal the 17th data point. For that reason, we can eliminate 2.5 and 3.5. If we were given an even number of data points, on the other hand, we could not immediately rule out 2.5 or 3.5. Why is that? Because if we had an even number of data points, the median would be the average of the middle two values, which could possibly equal a non-integer. In that case, we'd need to do more work to explore the data. Thanks for the question, and let me know if that helps!

[@anvayjoshi]

In the movie preview question at 22:09, how does Drama factor correlates with Funny one?

[@GMATNinjaTutoring]

The second question tells us that "each preview is made up entirely of comedy and drama." In other words, C + D = 100. So if something is 10 percent comedy, then it would have to be 90 percent drama. Given this, how does D correlate with C? Well, as C goes up, D must go down. For instance, if C increases from 10 to 40, then D would change from 90 to 60. Notice, by the same logic, we could also say that as D goes up, C must go down. Overall, this means that C and D are negatively correlated. But how does that help with the question -- what is the correlation between D and F? Looking at the graph, notice that as C goes up, F goes up. Or we could also say that as C goes down, F goes down. We also know that as C goes down, D goes up. Putting all that together, we could say that as D goes up, F goes down. That tells us that D and F are negatively correlated, which leads to the correct answer of B. I hope that helps!

[@anvayjoshi]

@@GMATNinjaTutoring Yes it does now. Thank you.

[@kanikamalhotra818]

What is the source of your DI questions? Asking so that I can practice more similar questions! TIA 🤔😄

[@GMATNinjaTutoring]

Everything in this video is an official GMAT question of one sort or another, and we strongly recommend sticking with official questions whenever possible for DI. If you don't already have it, the GMAT Official Guide bundle is essential: amzn.to/3Wx3bSg. There are also some additional official questions available for purchase at mba.com. I hope that helps, and have fun studying!

[@ryanbhatnagar]

How many episodes are there in this series?

[@GMATNinjaTutoring]

We should have about a dozen Data Insights videos once the series is complete. We usually publish one per week, but might accelerate that timeline a little bit -- keep an eye on the channel for more. Have fun studying!

[@shwetasood9164]

is there a way to calculate the percent change a bit faster and without writing so much because it is quite time consuming

[@GMATNinjaTutoring]

Great question! From the point of view of efficiency, consider the following steps: 1) Define p as the average value in 2006, and q as the average value in 2009 2) Since (average value) x (number of transactions) = total value of transactions, we could write the following equation: (22)(p)(11/10) = (20)(q) 3) Solve for q/p = 121/100 = 1.21 --> this means that q is 21% greater than p, which gives answer choice c. One additional thought -- test-takers often struggle with time not because they write out too much work, but because they skip a key step and go astray. So if writing out more work helps someone stay on track, it's probably a good investment. I hope that helps!

[@davidbrunik9998]

nice beard

[@nakulmandhre3897]

It is 121/100, not 121/10 :)

[@GMATNinjaTutoring]

Yes - that's absolutely correct! Embarrassing mistake on my part -- thank you so much for catching that!! The final answer is still C for that question (i.e. Question 5, Q2), but as you say, the calculation should read 121/100 = 1.21. Thanks again!