Oct 20 07:00 AM PDT  09:00 AM PDT Get personalized insights on how to achieve your Target Quant Score. Oct 22 09:00 AM PDT  10:00 AM PDT Watch & learn the Do's and Don’ts for your upcoming interview Oct 22 08:00 PM PDT  09:00 PM PDT On Demand for $79. For a score of 4951 (from current actual score of 40+) AllInOne Standard & 700+ Level Questions (150 questions) Oct 23 08:00 AM PDT  09:00 AM PDT Join an exclusive interview with the people behind the test. If you're taking the GMAT, this is a webinar you cannot afford to miss! Oct 26 07:00 AM PDT  09:00 AM PDT Want to score 90 percentile or higher on GMAT CR? Attend this free webinar to learn how to prethink assumptions and solve the most challenging questions in less than 2 minutes. Oct 27 07:00 AM EDT  09:00 AM PDT Exclusive offer! Get 400+ Practice Questions, 25 Video lessons and 6+ Webinars for FREE. Oct 27 08:00 PM EDT  09:00 PM EDT Strategies and techniques for approaching featured GMAT topics. One hour of live, online instruction
Author 
Message 
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 58434

Question Stats:
65% (00:47) correct 35% (00:56) wrong based on 83 sessions
HideShow timer Statistics
Each term of set \(T\) is a multiple of 5. Is standard deviation of \(T\) positive? (1) Each term of set \(T\) is positive (2) \(T\) consists of one term
Official Answer and Stats are available only to registered users. Register/ Login.
_________________



Math Expert
Joined: 02 Sep 2009
Posts: 58434

Re M0809
[#permalink]
Show Tags
16 Sep 2014, 00:36
Official Solution: The standard deviation of a set shows how much variation there is from the mean, how widespread a given set is. So, 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. So, basically we can say that it in a sense measures the distance and the distance cannot be negative, which means that the standard deviation of any set is greater than or equal to zero: \(SD \ge 0\). Next, the standard deviation of a set is zero if and only the set consists of identical numbers (or which is the same if the set consists of only one number). (1) Each term of set \(T\) is positive. If \(T=\{5\}\) then then \(SD=0\) but if set \(T=\{5, 10\}\) then \(SD \gt 0\). Not sufficient. (2) Set \(T\) consists of one term. Any set with only one term has the standard deviation equal to zero. Sufficient. Answer: B
_________________



Intern
Joined: 09 Aug 2014
Posts: 9

Re M0809
[#permalink]
Show Tags
19 Mar 2015, 03:09
I think this question is good and helpful.



Intern
Joined: 14 May 2014
Posts: 39
GPA: 3.11

Re: M0809
[#permalink]
Show Tags
24 Jul 2015, 08:07
Bunuel wrote: Official Solution:
The standard deviation of a set shows how much variation there is from the mean, how widespread a given set is. So, 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. So, basically we can say that it in a sense measures the distance and the distance cannot be negative, which means that the standard deviation of any set is greater than or equal to zero: \(SD \ge 0\). Next, the standard deviation of a set is zero if and only the set consists of identical numbers (or which is the same if the set consists of only one number). (1) Each term of set \(T\) is positive. If \(T=\{5\}\) then then \(SD=0\) but if set \(T=\{5, 10\}\) then \(SD \gt 0\). Not sufficient. (2) Set \(T\) consists of one term. Any set with only one term has the standard deviation equal to zero. Sufficient.
Answer: B dont we consider 0 as a positive no..? in that case both statements would be sufficient. pls help.



Math Expert
Joined: 02 Sep 2009
Posts: 58434

Re: M0809
[#permalink]
Show Tags
24 Jul 2015, 08:09
riyazgilani wrote: Bunuel wrote: Official Solution:
The standard deviation of a set shows how much variation there is from the mean, how widespread a given set is. So, 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. So, basically we can say that it in a sense measures the distance and the distance cannot be negative, which means that the standard deviation of any set is greater than or equal to zero: \(SD \ge 0\). Next, the standard deviation of a set is zero if and only the set consists of identical numbers (or which is the same if the set consists of only one number). (1) Each term of set \(T\) is positive. If \(T=\{5\}\) then then \(SD=0\) but if set \(T=\{5, 10\}\) then \(SD \gt 0\). Not sufficient. (2) Set \(T\) consists of one term. Any set with only one term has the standard deviation equal to zero. Sufficient.
Answer: B dont we consider 0 as a positive no..? in that case both statements would be sufficient. pls help. You should brush up fundamentals. ZERO:1. 0 is an integer. 2. 0 is an even integer. An even number is an integer that is "evenly divisible" by 2, i.e., divisible by 2 without a remainder and as zero is evenly divisible by 2 then it must be even. 3. 0 is neither positive nor negative integer (the only one of this kind).4. 0 is divisible by EVERY integer except 0 itself. Check more here: numberpropertiestipsandhints174996.html
_________________



Manager
Joined: 11 Oct 2013
Posts: 99
Concentration: Marketing, General Management

Re M0809
[#permalink]
Show Tags
18 Dec 2015, 04:16
I think this is a highquality question and I agree with explanation.
_________________



Intern
Joined: 22 Aug 2014
Posts: 38

It is very tricky because of two crucial facts: (1) SD is never negative. Think of its formula. SD is zero when single or same elements. (2) Zero is neither positive nor negative.



Intern
Joined: 25 Dec 2015
Posts: 2

Re: M0809
[#permalink]
Show Tags
15 Jan 2016, 21:04
Bunuel wrote: Official Solution:
The standard deviation of a set shows how much variation there is from the mean, how widespread a given set is. So, 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. So, basically we can say that it in a sense measures the distance and the distance cannot be negative, which means that the standard deviation of any set is greater than or equal to zero: \(SD \ge 0\). Next, the standard deviation of a set is zero if and only the set consists of identical numbers (or which is the same if the set consists of only one number). (1) Each term of set \(T\) is positive. If \(T=\{5\}\) then then \(SD=0\) but if set \(T=\{5, 10\}\) then \(SD \gt 0\). Not sufficient. (2) Set \(T\) consists of one term. Any set with only one term has the standard deviation equal to zero. Sufficient.
Answer: B Are we not required to find whether the SD is positive or not and from the answer you have provided does not A give us SD>0 ? So should not the answer be D instead of B ?



Math Expert
Joined: 02 Aug 2009
Posts: 7991

Re: M0809
[#permalink]
Show Tags
15 Jan 2016, 21:16
soumya90 wrote: Bunuel wrote: Official Solution:
The standard deviation of a set shows how much variation there is from the mean, how widespread a given set is. So, 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. So, basically we can say that it in a sense measures the distance and the distance cannot be negative, which means that the standard deviation of any set is greater than or equal to zero: \(SD \ge 0\). Next, the standard deviation of a set is zero if and only the set consists of identical numbers (or which is the same if the set consists of only one number). (1) Each term of set \(T\) is positive. If \(T=\{5\}\) then then \(SD=0\) but if set \(T=\{5, 10\}\) then \(SD \gt 0\). Not sufficient. (2) Set \(T\) consists of one term. Any set with only one term has the standard deviation equal to zero. Sufficient.
Answer: B Are we not required to find whether the SD is positive or not and from the answer you have provided does not A give us SD>0 ? So should not the answer be D instead of B ? Hi, we are required to find out if SD is positive... but we do not get a clear answer from A.. 1) if there is only one element, or all elements are same say 5,5,5.. SD = 0.. 2) if more than one and different, SD>0.. so SD can be 0, which is neither positive or negative or SD >0.. that is why insuff..
_________________



Manager
Joined: 22 Jun 2017
Posts: 168
Location: Argentina

Re M0809
[#permalink]
Show Tags
20 May 2018, 09:09
I think this is a highquality question and I agree with explanation.
_________________
The HARDER you work, the LUCKIER you get.



Intern
Joined: 22 Dec 2017
Posts: 9

Re: M0809
[#permalink]
Show Tags
07 Aug 2018, 09:43
Each term of set T is a multiple of 5. Is standard deviation of T positive?
(1) Each term of set T is positive
(2) T consists of one term Hi, the first statement is clearly not sufficient to answer the question about the SD. The second SD=0 and 0 is neither positive nor negative , so that still didn't answer our question whether SD is positive or negative . Please explain how statement 2 is sufficient.



Intern
Joined: 01 Apr 2018
Posts: 11
Location: India
Concentration: Strategy, Leadership
WE: Consulting (Consulting)

Re: M0809
[#permalink]
Show Tags
27 May 2019, 00:17
I think this is a highquality question and I agree with explanation.



Intern
Joined: 15 Oct 2017
Posts: 5

Re: M0809
[#permalink]
Show Tags
27 May 2019, 08:58
Bunuel wrote: Official Solution:
The standard deviation of a set shows how much variation there is from the mean, how widespread a given set is. So, 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. So, basically we can say that it in a sense measures the distance and the distance cannot be negative, which means that the standard deviation of any set is greater than or equal to zero: \(SD \ge 0\). Next, the standard deviation of a set is zero if and only the set consists of identical numbers (or which is the same if the set consists of only one number). (1) Each term of set \(T\) is positive. If \(T=\{5\}\) then then \(SD=0\) but if set \(T=\{5, 10\}\) then \(SD \gt 0\). Not sufficient. (2) Set \(T\) consists of one term. Any set with only one term has the standard deviation equal to zero. Sufficient.
Answer: B BunuelWhat i dont understand is that why shouldnt the answer be D. since from both we can answer the question whether the result is positive or not



Math Expert
Joined: 02 Sep 2009
Posts: 58434

chinmay96 wrote: Bunuel wrote: Official Solution:
The standard deviation of a set shows how much variation there is from the mean, how widespread a given set is. So, 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. So, basically we can say that it in a sense measures the distance and the distance cannot be negative, which means that the standard deviation of any set is greater than or equal to zero: \(SD \ge 0\). Next, the standard deviation of a set is zero if and only the set consists of identical numbers (or which is the same if the set consists of only one number). (1) Each term of set \(T\) is positive. If \(T=\{5\}\) then then \(SD=0\) but if set \(T=\{5, 10\}\) then \(SD \gt 0\). Not sufficient. (2) Set \(T\) consists of one term. Any set with only one term has the standard deviation equal to zero. Sufficient.
Answer: B BunuelWhat i dont understand is that why shouldnt the answer be D. since from both we can answer the question whether the result is positive or not The question asks whether SD is positive. From (2) in one case, when \(T=\{5\}\) the \(SD=0\) (so NOT positive) and in another case, when \(T=\{5, 10\}\) the \(SD \gt 0\) (so positive). Two answers. Not sufficient.
_________________










