If Q is a set of consecutive integers, what is the standard deviation of Q?
(1) Set Q contains 21 terms.
(2) The median of set Q is 20.
SD describes how much a set of data DEVIATES from the mean.
For any set of of consecutive integers, the mean = the median.
Question rephrased: How do the integers in set Q deviate from the median?
Statement 1: Set Q contains 21 terms.
Any set of 21 consecutive integers will deviate from the median EXACTLY THE SAME WAY.
If M = the median, the set will look like this:
M-10, M-9...M-2, M-1, M, M+1, M+2...M+9, M+10.
Thus, the SD can be determined.
SUFFICIENT.
Statement 2: Median = 20.
If there are only 3 terms -- if Q = {19, 20, 21} -- then there is very little deviation from the median.
If there are 101 terms, then there will be quite a bit of deviation from the median.
Thus, the SD can be different values.
INSUFFICIENT.
The correct answer is
A.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at
[email protected].
Student Review #1
Student Review #2
Student Review #3
