Check GMAT Club Decision Tracker for the Latest School Decision Releases https://gmatclub.com/AppTrack

 It is currently 23 May 2017, 15:46

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# In the last two years, each of Jeremys six children grew in

Author Message
TAGS:

### Hide Tags

Retired Moderator
Status: 2000 posts! I don't know whether I should feel great or sad about it! LOL
Joined: 04 Oct 2009
Posts: 1672
Location: Peru
Schools: Harvard, Stanford, Wharton, MIT & HKS (Government)
WE 1: Economic research
WE 2: Banking
WE 3: Government: Foreign Trade and SMEs
Followers: 103

Kudos [?]: 992 [1] , given: 109

In the last two years, each of Jeremys six children grew in [#permalink]

### Show Tags

12 Apr 2012, 16:05
1
KUDOS
00:00

Difficulty:

35% (medium)

Question Stats:

77% (06:07) correct 23% (00:58) wrong based on 56 sessions

### HideShow timer Statistics

In the last two years, each of Jeremys six children grew in height by at least one inch. If the standard deviation of their heights two years ago was 4.5 inches, what is the standard deviation of their heights?

(1) In the last two years, the heights of Jeremys six children have increased a total of 17 inches.
(2) In the last two years, each childs height has increased by 5 percent.

Source: http://www.gmathacks.com
[Reveal] Spoiler: OA

_________________

"Life’s battle doesn’t always go to stronger or faster men; but sooner or later the man who wins is the one who thinks he can."

My Integrated Reasoning Logbook / Diary: http://gmatclub.com/forum/my-ir-logbook-diary-133264.html

GMAT Club Premium Membership - big benefits and savings

Math Expert
Joined: 02 Sep 2009
Posts: 38841
Followers: 7718

Kudos [?]: 105919 [1] , given: 11593

Re: In the last two years, each of Jeremys six children grew in [#permalink]

### Show Tags

12 Apr 2012, 17:25
1
KUDOS
Expert's post
1
This post was
BOOKMARKED
In the last two years, each of Jeremys six children grew in height by at least one inch. If the standard deviation of their heights two years ago was 4.5 inches, what is the standard deviation of their heights?

We are given a set with 6 terms and the standard deviation of 4.5. Next, we are told that each term of this set was increased and are asked to find the new standard deviation of this changed set.

(1) In the last two years, the heights of Jeremys six children have increased a total of 17 inches. Not sufficient, since many different scenarios of increase of each data point are possible.

(2) In the last two years, each childs height has increased by 5 percent. Important property: if we increase or decrease each term in a set by the same percent (multiply all terms by the constant): SD will increase or decrease by the same percent. So, since each of 6 terms has increased by 5% then the standard deviation of 4.5 would also increase by 5% and become 4.5*1.05. Sufficient.

_________________
GMAT Club Legend
Joined: 09 Sep 2013
Posts: 15406
Followers: 648

Kudos [?]: 205 [0], given: 0

Re: In the last two years, each of Jeremys six children grew in [#permalink]

### Show Tags

29 Mar 2017, 05:38
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
Re: In the last two years, each of Jeremys six children grew in   [#permalink] 29 Mar 2017, 05:38
Similar topics Replies Last post
Similar
Topics:
1 If each child in a group of children received either one or two pieces 2 04 Mar 2017, 06:15
1 Last year Roger, Shelly,and Terry each contributed money to a certain 5 02 Oct 2016, 23:52
4 In each of the last five years, Company K donated p percent of its 5 06 Dec 2016, 08:29
2 Over the last two years who made more investing in stock 7 13 May 2015, 03:49
5 Last year the first \$ 30,000 of each Country X resident's 2 29 Mar 2017, 05:47
Display posts from previous: Sort by