The graph shows the annual amount of salt (sodium chloride or NaC)

Question

The graph shows the annual amount of salt (sodium chloride, or NaCl) used on roads in Nation X, for the purpose of melting snow and ice. The natural deposition is the average amount of salt that would be deposited on the surface of the country (by, for example, rainfall), regardless of human activities.

This use of salt has resulted in considerably increased concentrations of both sodium (Na) and chloride (Cl) in the country's surface water (rivers, streams, lakes)–sufficient to be toxic in both plants and fish, and for significant adverse human health effects due to increased salt intake. However, because sodium passes less easily through soils than chloride passes, the levels of extra sodium in the country's aquifers (underground water) are notably lower than the levels of extra chloride, and likely negligible in most locations.

Bismuth83 · Accepted Answer

1. The question asks us whether the information can say that a difference in a quality is statistically significant. The text says that "differences are statistically significant when the experimental error intervals do not intersect".

2. Measured amounts of sodium in drinking water derived from aquifers. The text states that "the levels of extra sodium in the country's aquifers (underground water) are notably lower than the levels of extra chloride, and likely negligible in most locations". That means the difference in the quantity isn't statistically significant.

3. Measured relative eye widths of male monarch butterflies. Looking at the left part of the bar chart, we can say that the intervals do intersect. That means the difference in the quantity isn't statistically significant.

4. Measured relative eye widths of female monarch butterflies. Looking at the right part of the bar chart, we can say that the intervals don't intersect. That means the difference in the quantity is statistically significant.

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guddo · Answer

https://gmatclub.com/forum/download/file.php?id=82930 GMAT-Club-Forum-bjw7w51y.png

Shreejas · Answer

Please explain the solutions

sachi-in · Answer

1. Na difference in places with excess salt and places without it is very small, even non-existent in cases - Statistically insignificant changes
2. Error ranges don't overlap hence statistically significant differences
3. Error ranges overlap hence Statistically insignificant changes

Imagine a quantity Q = 100 (with error range 10%) i.e Actual Q = 90 - 100
Another quantity Q2 = 90 ( with error range 20% ) i.e Actual Q2 = 72 - 108

Thus actual values of A and Q2 overlap hence we can't deterministically say they are different values.

shriyaapathi · Answer

I did not understand the 1st question solution. How is it done ?

satish_sahoo · Answer

Hi,

Does this set consists of only 1 question?

Can,Will · Answer

I did not understand the question,at all .
It took me long to understand what is being asked in the question , and still confused .

Bismuth83 · Answer

What exactly do you not understand?

The question asks about three types of information and asks about each one whether it's statistically significant. This means whether the numbers from the information are large enough or have a large difference so that it would be valuable in the discussion.

Hopefully that helped!

GuiguiECL · Answer

How can we assume drinking water is underground water ?

Bismuth83 · Answer

The data that we're interested in is drinking water derived from aquifers (which is where underground water is located). So, all drinking water is not assumed to be from underground.

I hope that helped!

SSWTtoKellogg · Answer

Hi  Bismuth83   KarishmaB , could you please explain why does " Measured amounts of sodium in drinking water derived from aquifers" not significant? The 3rd tab, it has been mentioned as one of the reasons.

Globethrotter · Answer

Tab 1 states  factually  that level of extra sodium in underground water due to salting of roads is  negligible . Tab 3 is mentioned as a conversation between two ordinary residents, so what they say can only be taken as  opinions  and need not be factually correct. For all we know he might be ignorant and might not have read/studied about the issue or relevant data, and hence probably giving a flawed reasoning.

Harsh020 · Answer

This question looks kinda brutal. When we see MSR, we go through the entire data and then maybe expect 3-4 questions. But here, you just see one question after digesting all that data. I hope this is not the case in the actual exam.

FrozenDragon · Answer

Yes, I think this is just for practice. In Exam, You will most probably never find just 1 question for particular MSR. at least 2 question will be there for you to answer.

FrozenDragon · Answer

Yes, but do we know for sure that resident is talking about  drinking water  derived from aquifers.    if not, then we can't conclude anything.

The graph shows the annual amount of salt (sodium chloride or NaC)

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Yes	No
		Measured amounts of sodium in drinking water derived from aquifers
		Measured relative eye widths of male monarch butterflies
		Measured relative eye widths of female monarch butterflies

GMAT Multi-Source Reasoning (MSR) Questions

The graph shows the annual amount of salt (sodium chloride or NaC)

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

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My Rewards