Oneva wrote:... i don't have a very comfortable understanding of standard deviations.
For a data set, standard deviation is the measure of
dispersion or
variation of the data from the mean or average. A low standard deviation indicates that the data points tend to be very close to the mean, whereas high standard deviation indicates that the data are spread out over a large range of values.
It is defined as the the square root of the average of the squared differences from the Mean. Yes, the definition seems a bit confusing. For a explained definition with an example, visit this link :
https://www.mathsisfun.com/data/standard-deviation.html
But for this particular question, we don't need to use those concepts.
Oneva wrote:If the standard deviation of Set Y is 4, what are the greatest and least values that are within one standard deviation of the mean?
(1) The median of Set Y is 5
(2) The mean of Set Y is 6
If we just omit the term "standard deviation" from the question, then the question is asking
What are the greatest and least values that are within a distance of 4 from the mean?
Hence, if we know the mean, we can easily determine those values as greatest = (Mean + 4) and least = (Mean - 4)
Now, statement 1 is NOT sufficient as it doesn't provide the mean. Buts statement 2 is SUFFICIENT.
The correct answer is B.
