I03-09

Question

https://gmatclub.com/gmat-focus-tests/resources/import/img/I03-09.png 
 
The graph shows the minimum, maximum, and mean sea-surface temperatures (with the mean indicated by —), as well as the terminal growth band SST (indicated by •) recorded for 20 sampled shells. The terminal growth band SST refers to the sea-surface temperature at the time the shell stopped growing.
 
Select from each drop-down menu the option that creates the most accurate statement, given the information provided.

The range of temperatures observed across all shells is approximately  GRAPH_1_PLACEHOLDER °C.

The median terminal growth band SST for all sampled shells is  GRAPH_2_PLACEHOLDER  the average of the mean SSTs for all shells.

Bunuel · Answer

Official Solution:

Drop-down 1: 
 
From the graph, we can see that the highest temperature recorded for a shell was approximately 24°C (for shell #13), while the lowest temperature recorded was approximately 12°C (for shell #15). Therefore, the range of temperatures observed across all shells is approximately 24 - 12 = 12°C.
 
 Drop-down 2: 
 
The median of 20 data points is calculated as the average of the two middle terms when the data is arranged in order. Observing the graph, we see that 9 terminal growth band SSTs are at or below 15°C. The 10th and 11th largest values, which determine the median, are slightly above 15°C and correspond to approximately 16°C for shells #4 and #14. Thus, the median is 16°C.
 
However, the mean SSTs for most shells are well above 16°C (except for shells #15 and #20, where they are slightly below 16°C). Therefore, the average of the mean SSTs, with most values well above 16°C and only two slightly below, will also be higher than 16°C. Hence, the median terminal growth band SST for all sampled shells is less than the average of the mean SSTs for all shells.

Correct answer:

Dropdown 1:  "12"

Dropdown 2:  "less than"

Bunuel · Answer

I have revised the question, solution, and formatting by adding more details to enhance clarity

Dbrunik · Answer

I think this is a  high-quality  question and I agree with explanation.

colhaox · Answer

I like the solution - it’s helpful.

colleg21 · Answer

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Edwin555 · Answer

I like the solution - it’s helpful. These are some nice tricky question! Thanks!

RustamBh · Answer

I like the solution - it’s helpful.

CapnSal · Answer

I did not quite understand the solution. Can we just compare how many times the mean is above the median? if we calculate the number of such instances, we have 14 such shells so we can be sure that the mean is greater than the median (or the median is less than the mean)?

Bunuel · Answer

We don’t have the median terminal growth band SST shown. What we have are the individual terminal growth band SSTs (the black dots) for 20 shells, so we need to calculate the median ourselves.

Also, we’re not given the average of the mean SSTs. We only have the individual mean SSTs (the short horizontal lines on the bars), and we need to calculate their average.

So no, you can’t just “compare” without first calculating both values.

Mayank_1206 · Answer

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YOGEESHREDDI · Answer

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FzBdr · Answer

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FzBdr · Answer

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I03-09

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