Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 22 May 2015, 23:25

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

Set S consists of n numbers arranged in ascending order. A

Author Message
TAGS:
Manager
Joined: 04 Jan 2008
Posts: 120
Followers: 2

Kudos [?]: 23 [0], given: 0

Set S consists of n numbers arranged in ascending order. A [#permalink]  05 Sep 2008, 20:59
00:00

Difficulty:

45% (medium)

Question Stats:

60% (02:26) correct 40% (01:06) wrong based on 68 sessions
Set S consists of n numbers arranged in ascending order. A new set is created as follows: each element of set S is increased by a value equal to that number's place within the set (i.e. the lowest number is increased by 1, the second lowest is increased by 2, etc.). By how much is the mean of the new set greater than the mean of the original set ?

(1) Set S consists of 10 elements
(2) The sum of the elements in the original set is 100
[Reveal] Spoiler: OA
Director
Joined: 23 Sep 2007
Posts: 794
Followers: 5

Kudos [?]: 101 [0], given: 0

Re: Zumit DS 006 [#permalink]  05 Sep 2008, 21:23
dancinggeometry wrote:
Set S consists of n numbers arranged in ascending order. A new set is created as follows: each element of set S is increased by a value equal to that number's place within the set (i.e. the lowest number is increased by 1, the second lowest is increased by 2, etc.). By how much is the mean of the new set greater than the mean of the original set ?

(1) Set S consists of 10 elements
(2) The sum of the elements in the original set is 100

A

sum of the original set + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10
The average will increase by 5.5
VP
Joined: 17 Jun 2008
Posts: 1404
Followers: 8

Kudos [?]: 153 [0], given: 0

Re: Zumit DS 006 [#permalink]  05 Sep 2008, 21:28
dancinggeometry wrote:
Set S consists of n numbers arranged in ascending order. A new set is created as follows: each element of set S is increased by a value equal to that number's place within the set (i.e. the lowest number is increased by 1, the second lowest is increased by 2, etc.). By how much is the mean of the new set greater than the mean of the original set ?

(1) Set S consists of 10 elements
(2) The sum of the elements in the original set is 100

(1) says n=10 => increased value is n(n+1)/2 =55 when n=10
hence increase in average can be obtained.SUFFI
(2)sum is 100 does not say anythin about n hence INSUFFI
IMOA
_________________

cheers
Its Now Or Never

Intern
Joined: 05 Sep 2008
Posts: 13
Followers: 0

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

Re: Zumit DS 006 [#permalink]  05 Sep 2008, 21:48
A also.

In order to solve this probem you need to know how many elements are in the set.

st 2 does not show how many elements are in the set so just knowing the sum would not help.
Manager
Joined: 04 Jan 2008
Posts: 120
Followers: 2

Kudos [?]: 23 [0], given: 0

Re: Zumit DS 006 [#permalink]  06 Sep 2008, 23:06
OA is A. Bin 3 problem.
Intern
Joined: 26 Sep 2012
Posts: 17
Followers: 0

Kudos [?]: 7 [0], given: 1

Re: Set S consists of n numbers arranged in ascending order. A [#permalink]  28 May 2013, 23:16
By plugging numbers I discovered that the difference (new median - old median) can be calculated from the formula:
(n+1)/2. Experienced mathematicians must know this effect with sets and the formula.

However, if you are an average GMAT test taker, like me, IMO, the best way to solve was found by gmatnub

gmatnub wrote:
Set S consists of n numbers arranged in ascending order. A new set is created as follows: each
sum of the original set + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10
The average will increase by 5.5
Intern
Joined: 26 Sep 2012
Posts: 17
Followers: 0

Kudos [?]: 7 [0], given: 1

Re: Set S consists of n numbers arranged in ascending order. A [#permalink]  28 May 2013, 23:45
After a while I got the following:

Basically, to obtain a new set we add another set (1, 2, 3, 4, 5, ... n) [Let's name this set as set N] to a first set. As the set N is a set of consecutive numbers, so we can calculate its median. To locate the median we should find the average of the first number and the last number of the set N:
(n+1)/2.
As we know the mean is equal to the median of the same set of consecutive numbers. So, the difference between the mean of a first set and that of a new set can be found if we know the number n of elements of either first or last sets.
SVP
Joined: 06 Sep 2013
Posts: 2045
Concentration: Finance
GMAT 1: 770 Q0 V
Followers: 26

Kudos [?]: 301 [0], given: 354

Re: Set S consists of n numbers arranged in ascending order. A [#permalink]  12 Oct 2013, 15:35
dancinggeometry wrote:
Set S consists of n numbers arranged in ascending order. A new set is created as follows: each element of set S is increased by a value equal to that number's place within the set (i.e. the lowest number is increased by 1, the second lowest is increased by 2, etc.). By how much is the mean of the new set greater than the mean of the original set ?

(1) Set S consists of 10 elements
(2) The sum of the elements in the original set is 100

Guys remember arranged in ascending order doesn't mean that they are consecutive.
Keep that in mind, GMAT sometimes tries to trick you like this

Good luck
Cheers
J
Manager
Joined: 27 May 2012
Posts: 214
Followers: 0

Kudos [?]: 50 [0], given: 400

Re: Zumit DS 006 [#permalink]  20 Dec 2013, 02:18
gmatnub wrote:
dancinggeometry wrote:
Set S consists of n numbers arranged in ascending order. A new set is created as follows: each element of set S is increased by a value equal to that number's place within the set (i.e. the lowest number is increased by 1, the second lowest is increased by 2, etc.). By how much is the mean of the new set greater than the mean of the original set ?

(1) Set S consists of 10 elements
(2) The sum of the elements in the original set is 100

A

sum of the original set + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10
The average will increase by 5.5

Just couldn't understand the explanations, here is my small take hope it helps others

average is given by sum of total elements / number of elements

statement 1 : Set S consists of 10 elements

let the sum of the original 10 elements be x , average is $$\frac{x}{10}$$
the new set is formed and its total will be x+55 . Average of new set $$\frac{x+55}{10}$$

Now average increase will be $$\frac{x+55}{10} - \frac{x}{10} = 5.5$$
Hence A is sufficient
Hope it helps.
_________________

- Stne

Re: Zumit DS 006   [#permalink] 20 Dec 2013, 02:18
Similar topics Replies Last post
Similar
Topics:
2 If set S consists of the numbers n, -2, and 4... 2 24 Jun 2013, 11:54
4 Set S consists of 5 values, not necessarily in ascending 5 12 Dec 2012, 13:36
4 Set X consists of different positive numbers arranged in ascending ord 6 17 Nov 2011, 15:41
Set s consists of n numbers arranged in ascending series. A 3 12 Aug 2006, 20:00
Sequence: An arrangement of numbers in a definite order 6 16 Jan 2006, 09:23
Display posts from previous: Sort by