Post your question in the Comment section below, and a GRE expert will answer it as fast as humanly possible.
- Video Course
- Video Course Overview
- General GRE Info and Strategies - 7 videos (free)
- Quantitative Comparison - 7 videos (free)
- Arithmetic - 42 videos
- Powers and Roots - 43 videos
- Algebra and Equation Solving - 78 videos
- Word Problems - 54 videos
- Geometry - 48 videos
- Integer Properties - 34 videos
- Statistics - 28 videos
- Counting - 27 videos
- Probability - 25 videos
- Data Interpretation - 24 videos
- Analytical Writing - 9 videos (free)
- Sentence Equivalence - 39 videos (free)
- Text Completion - 51 videos
- Reading Comprehension - 16 videos
- Study Guide
- Philosophy
- Office Hours
- Extras
- Prices
Comment on Ordering Standard Deviations
Hello. In Data Set II, I see
Median = mean when all of the
Median = mean when all of the values in a set are equally spaced.
If there is an odd number of values, the median is the middlemost value, but we can't make any conclusions about the mean.
Here's the video on when the median = the mean: https://www.greenlighttestprep.com/module/gre-statistics/video/804
Is it possible for range to
For example,the higher the range,the higher the S.D.
II has the highest S.D because it has a range of 3 followed by III which has a range of 2 then finally I because it has range of 0.2.
Sometimes the set with the
Sometimes the set with the greatest range will also be the set with the greatest Standard Deviation, but this isn't always the case.
Consider these two sets:
Set A: {0, 5, 5, 5, 5, 5, 5, 5, 10}
Set B: {0, 0, 0, 0, 4, 8, 8, 8, 8}
Set A has a mean of 5.
Notice that 7 of the values in set A are equal to the mean.
The remaining values (0 and 10) are each 5 units from the mean
Set B has a mean of 4.
Notice that only 1 value in set B is equal to the mean.
The remaining values (0, 0, 0, 0, 8, 8, 8 and 8) are each 4 units from the mean
If we think about Standard Deviation as the average distance from the mean, we can see that the Standard Deviation of Set B is greater than the Standard Deviation of Set A, EVEN THOUGH the range of Set A is greater than the range of Set B.
Does that help?
Cheers,
Brent
Hi Brent,
can we just find the greatest standard deviation by subtracting the last number of the set with first number as its mentioned in your previous lesson(https://www.greenlighttestprep.com/module/gre-statistics/video/806) at 08.02 minute. Or i understood it wrong?
No, that isn't correct.
No, that isn't correct.
For example, the standard deviation of {1,3,5} is greater than the standard deviation of {1,3,3,3,3,3,3,5}.
You can see why this is the case if you apply the informal definition of standard deviation described here https://www.greenlighttestprep.com/module/gre-statistics/video/806