November 14, 2018 November 14, 2018 07:00 PM PST 08:00 PM PST Join the webinar and learn timemanagement tactics that will guarantee you answer all questions, in all sections, on time. Save your spot today! Nov. 14th at 7 PM PST November 15, 2018 November 15, 2018 10:00 PM MST 11:00 PM MST EMPOWERgmat is giving away the complete Official GMAT Exam Pack collection worth $100 with the 3 Month Pack ($299)
Author 
Message 
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 50572

The students in two classes of "Underachiever" high school took a test
[#permalink]
Show Tags
26 Sep 2016, 02:12
Question Stats:
71% (01:46) correct 29% (01:47) wrong based on 166 sessions
HideShow timer Statistics
The students in two classes of "Underachiever" high school took a test. x, a, and c are, respectively, the standard deviation, median and the mean of the test scores of the students in class X. y, b, and d are, respectively, the standard deviation, median and mean of the test scores of the students in class Y. Is x>y? (1) a < b (2) c < d
Official Answer and Stats are available only to registered users. Register/ Login.
_________________
New to the Math Forum? Please read this: Ultimate GMAT Quantitative Megathread  All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics



Manager
Joined: 24 Oct 2013
Posts: 141
Location: India
Concentration: General Management, Strategy
WE: Information Technology (Computer Software)

Re: The students in two classes of "Underachiever" high school took a test
[#permalink]
Show Tags
27 Sep 2016, 01:05
Even if we know mean and median, to definitely derive SD we should know individual data of each class
Hence SD can not be determined. I choose E



Intern
Joined: 23 Jun 2016
Posts: 41

Re: The students in two classes of "Underachiever" high school took a test
[#permalink]
Show Tags
27 Sep 2016, 10:30
Statement 1 insufficient because median doesn't tell us anything about the number in the set and the values in the set Statement 2 insufficient because the mean doesn't tell us the number in the sets of their values
When we combine them same issue
IMO E



Intern
Joined: 01 Jul 2014
Posts: 27
Location: India
GPA: 3.2

The students in two classes of "Underachiever" high school took a test
[#permalink]
Show Tags
27 Sep 2016, 11:54
Given: Two classes X and Y X: x (standard deviation), a (median), and c (mean) Y: y (standard deviation), b (median), and d (mean)
Is x>y?
(1) a < b Let's assume Scores in class X: 10, 20, 30 Scores in class Y: 20, 30,40 a = 20 , b = 30 ==> a<b standard deviation will be same in both cases (evenly spaced set with same difference) ==> x=y=10, Is x>y = NO
Now assume scores in class Y: 24,25,26 b=25 ==> Now the standard deviation is 1, x=10 and y=1, Is x>y = YES
Hence not sufficient.
(2) c < d Consider the above scenarios We will get both answers (yes and no) to "Is x>y" in this case
(1)+(2) is not adding anything new, so it won't be sufficient
Hence E



Manager
Joined: 01 Jun 2015
Posts: 219
Location: India
Concentration: Strategy, International Business

Re: The students in two classes of "Underachiever" high school took a test
[#permalink]
Show Tags
09 Mar 2017, 22:26
Standard Deviation is the distance of the scores from the mean.So getting the mean or median will not give any information on SD.Hence answer is E.



Intern
Joined: 24 Jan 2017
Posts: 15
Location: Brazil
Concentration: Strategy, Entrepreneurship
GPA: 3.5
WE: Consulting (Consulting)

Re: The students in two classes of "Underachiever" high school took a test
[#permalink]
Show Tags
15 Dec 2017, 05:23
deepthit wrote: Even if we know mean and median, to definitely derive SD we should know individual data of each class
Hence SD can not be determined. I choose E Not necessarily! If we knew that the sets had the same number and were evenly spaced, we could find the answer. In this case (statements), x<y.




Re: The students in two classes of "Underachiever" high school took a test &nbs
[#permalink]
15 Dec 2017, 05:23






