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

 It is currently 26 Nov 2015, 23:41

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

If set s={7,y,12,8,,x,9} is x+y less than 18? 1.range of set

Author Message
TAGS:
Manager
Joined: 11 Feb 2011
Posts: 134
Followers: 3

Kudos [?]: 87 [1] , given: 21

If set s={7,y,12,8,,x,9} is x+y less than 18? 1.range of set [#permalink]  23 Mar 2011, 23:50
1
KUDOS
00:00

Difficulty:

(N/A)

Question Stats:

50% (02:48) correct 50% (00:57) wrong based on 30 sessions
If set s={7,y,12,8,,x,9} is x+y less than 18?

1.range of set s is less than 9
2.average of x and y is less than average of set s.
_________________

target:-810 out of 800!

SVP
Joined: 16 Nov 2010
Posts: 1676
Location: United States (IN)
Concentration: Strategy, Technology
Followers: 32

Kudos [?]: 401 [0], given: 36

Re: explain the concept ! [#permalink]  24 Mar 2011, 01:19
If range is less than 9, then the difference between the largest and teh smallest members of the set should be ,9

The difference of all the given numbers < 9

So even if we were to assume that the difference between x and y is less than 18

then let us try to find values of x and y

So x = 7 + 10 = 17

y can be the same as well = 7 + 10 = 17

So x + y can be > 18,

Again, x+y can be any other numbers as 1 and 2, and the range is still < 9.

so (1) is not sufficient.

From (2)

(x+y)/2 < (7 + y + 12 + 8 + x + 9)/6

=> 6(x+y) < 2(x+y + 36)

=> 4(x+y) < 2*36

=> (x+y) < 18

_________________

Formula of Life -> Achievement/Potential = k * Happiness (where k is a constant)

GMAT Club Premium Membership - big benefits and savings

Director
Status: No dream is too large, no dreamer is too small
Joined: 14 Jul 2010
Posts: 649
Followers: 37

Kudos [?]: 486 [0], given: 39

Re: explain the concept ! [#permalink]  25 Mar 2011, 05:22
AnkitK wrote:
If set s={7,y,12,8,,x,9} is x+y less than 18?

1.range of set s is less than 9
2.average of x and y is less than average of set s.

(1) x= 5, y= 11 range (12-5) is less than 9 and x+y <18
but x= 5, y= 13 here range is less than 8 but x+y=18 so INSUFFICIENT.

(2) (X+Y)/2<(7+y+12+8+x+9)/6
X+Y<18 SUFF.
ANS B
_________________

Collections:-
PSof OG solved by GC members: http://gmatclub.com/forum/collection-ps-with-solution-from-gmatclub-110005.html
DS of OG solved by GC members: http://gmatclub.com/forum/collection-ds-with-solution-from-gmatclub-110004.html
100 GMAT PREP Quantitative collection http://gmatclub.com/forum/gmat-prep-problem-collections-114358.html
Collections of work/rate problems with solutions http://gmatclub.com/forum/collections-of-work-rate-problem-with-solutions-118919.html
Mixture problems in a file with best solutions: http://gmatclub.com/forum/mixture-problems-with-best-and-easy-solutions-all-together-124644.html

Re: explain the concept !   [#permalink] 25 Mar 2011, 05:22
Similar topics Replies Last post
Similar
Topics:
4 Set S consists of all the positive multiples of 5 that are less than K 2 18 Mar 2015, 04:12
2 If set S = {7, y, 12, 8, x, 9}, is x + y less than 18? 2 14 Oct 2014, 05:11
Set A consists of all positive integers less than 100; Set B 2 29 Nov 2013, 01:41
A non empty set S has less than four elements. How many 4 25 Jul 2013, 06:25
1 If xy=-18, is x less than y? 5 07 Apr 2013, 00:43
Display posts from previous: Sort by