Author 
Message 
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 39589

Last year Department Store X had a sales total for December [#permalink]
Show Tags
05 Mar 2014, 02:12
1
This post received KUDOS
Expert's post
4
This post was BOOKMARKED
Question Stats:
63% (02:14) correct
37% (01:19) wrong based on 503 sessions
HideShow timer Statistics
The Official Guide For GMAT® Quantitative Review, 2ND EditionLast year Department Store X had a sales total for December that was 4 times the average (arithmetic mean) of the monthly sales totals for January through November. The sales total for December was what fraction of the sales total for the year? (A) 1/4 (B) 4/15 (C) 1/3 (D) 4/11 (E) 4/5 Problem Solving Question: 129 Category: Algebra; Arithmetic Applied problems; Statistics Page: 78 Difficulty: 600 GMAT Club is introducing a new project: The Official Guide For GMAT® Quantitative Review, 2ND Edition  Quantitative Questions ProjectEach week we'll be posting several questions from The Official Guide For GMAT® Quantitative Review, 2ND Edition and then after couple of days we'll provide Official Answer (OA) to them along with a slution. We'll be glad if you participate in development of this project: 1. Please provide your solutions to the questions; 2. Please vote for the best solutions by pressing Kudos button; 3. Please vote for the questions themselves by pressing Kudos button; 4. Please share your views on difficulty level of the questions, so that we have most precise evaluation. Thank you!
Official Answer and Stats are available only to registered users. Register/ Login.
_________________
New to the Math Forum? Please read this: 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



Math Expert
Joined: 02 Sep 2009
Posts: 39589

Re: Last year Department Store X had a sales total for December [#permalink]
Show Tags
05 Mar 2014, 02:12
1
This post received KUDOS
Expert's post
2
This post was BOOKMARKED



Intern
Status: Trying to beat the gmat
Joined: 19 Nov 2012
Posts: 42
Location: Brazil
Concentration: General Management, Entrepreneurship

Re: Last year Department Store X had a sales total for December [#permalink]
Show Tags
05 Mar 2014, 15:57
Lets consider each month sales as X, the december sales is 4 times the average of the other months, so december is 4X, to define what fraction of the total year sales must be fraction / total so will be 4x / 11x + 4x, 4x / 16x, and will be



Moderator
Joined: 20 Dec 2013
Posts: 189
Location: United States (NY)
GMAT 1: 640 Q44 V34 GMAT 2: 710 Q48 V40 GMAT 3: 720 Q49 V40
GPA: 3.16
WE: Consulting (Venture Capital)

Re: Last year Department Store X had a sales total for December [#permalink]
Show Tags
05 Mar 2014, 17:20
1
This post received KUDOS
JanNov Avg Monthly Sales:Dec Sales 1:4 Dec Sales/(JanNov Sales Total+Dec Sales) 4/[(11*1)+(1*4)] 4/15 B
_________________
MY GMAT BLOG  ADVICE  OPINIONS  ANALYSIS



Manager
Status: GMATting
Joined: 21 Mar 2011
Posts: 108
Concentration: Strategy, Technology

Re: Last year Department Store X had a sales total for December [#permalink]
Show Tags
05 Mar 2014, 21:28
1
This post received KUDOS
Let the monthy sales, on average, be x. Monthly sales totals for January through November = 11x; Sales Total for December = 4x;
We can write the equation: 4x/(11x + 4x) = 4x/15x = 4/15;
Ans is (B)



SVP
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1857
Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)

Re: Last year Department Store X had a sales total for December [#permalink]
Show Tags
06 Mar 2014, 03:08
1
This post received KUDOS
Let sales from Jan to Nov = J + F +....... +N Let sales in December = d \(Avg = \frac{(J + F +....... +N)}{11}\) \(d = 4 * \frac{(J + F +....... +N)}{11}\) \((J + F +....... +N) = \frac{11d}{4}\) ...... Sales from Jan through Nov Total sales Jan to Dec \(= \frac{11d}{4} + d = \frac{15d}{4}\) The sales total for December is \(\frac{4}{15}\) fraction of the sales total for the year Answer = B
_________________
Kindly press "+1 Kudos" to appreciate



Director
Joined: 25 Apr 2012
Posts: 727
Location: India
GPA: 3.21
WE: Business Development (Other)

Re: Last year Department Store X had a sales total for December [#permalink]
Show Tags
06 Mar 2014, 04:02
1
This post received KUDOS
Last year Department Store X had a sales total for December that was 4 times the average (arithmetic mean) of the monthly sales totals for January through November. The sales total for December was what fraction of the sales total for the year?
(A) 1/4 (B) 4/15 (C) 1/3 (D) 4/11 (E) 4/5
Sol: Let the average sale for Jan to Nov period is X then total sales in this period is 11X Now sale in Dec 4X. Total sale for JanDec: 15X Dec sale as fraction of Total sales 4X/15X or 4/15 Ans is B
_________________
“If you can't fly then run, if you can't run then walk, if you can't walk then crawl, but whatever you do you have to keep moving forward.”



Manager
Joined: 01 May 2013
Posts: 62

Re: Last year Department Store X had a sales total for December [#permalink]
Show Tags
06 Mar 2014, 15:34
1
This post received KUDOS
Plugged in numbers. Set average to 1. Total for JanNov is 11. Sales for Dec = 4. Yearly total 15. Dec = 4/15 of total.



Senior Manager
Joined: 20 Dec 2013
Posts: 267
Location: India

Re: Last year Department Store X had a sales total for December [#permalink]
Show Tags
08 Mar 2014, 06:51
1
This post received KUDOS
Let sum of sales from Jan to Nov=x Sales in dec=y To calculate:y/x+y We're given 4x/11=y x/y=11/4 Add 1 to both sides and reciprocate. We get 4/15 Option B.
Posted from my mobile device



Math Expert
Joined: 02 Sep 2009
Posts: 39589

Re: Last year Department Store X had a sales total for December [#permalink]
Show Tags
08 Mar 2014, 12:29



Director
Joined: 23 Jan 2013
Posts: 585

Re: Last year Department Store X had a sales total for December [#permalink]
Show Tags
01 Dec 2014, 21:19
By picking:
x/11=2, 22 in eleven months
2*4=8 in December, so
8/22+8=8/30=4/15
B



Intern
Status: I am working with SageNext Infotech LLC as a system Engineer. SageNext is a leading QuickBooks Hosting provider.
Joined: 01 Dec 2014
Posts: 1
Location: United States

Re: Last year Department Store X had a sales total for December [#permalink]
Show Tags
01 Dec 2014, 21:25
We absolutely love your post and find a lot of your post’s to be exactly I’m looking for. Does one offer guest writers to write content for you personally? I wouldn’t mind creating a post or elaborating on a lot of the subjects you write regarding here. Again, awesome weblog!



Director
Joined: 10 Mar 2013
Posts: 597
Location: Germany
Concentration: Finance, Entrepreneurship
GPA: 3.88
WE: Information Technology (Consulting)

Re: Last year Department Store X had a sales total for December [#permalink]
Show Tags
16 Nov 2015, 13:23
Bunuel wrote: The Official Guide For GMAT® Quantitative Review, 2ND EditionLast year Department Store X had a sales total for December that was 4 times the average (arithmetic mean) of the monthly sales totals for January through November. The sales total for December was what fraction of the sales total for the year? (A) 1/4 (B) 4/15 (C) 1/3 (D) 4/11 (E) 4/5 We can use just some smart numbers here December = 8; means that the average for each month JanNov = 2 > \(\frac{8}{8+11*2}=\frac{4}{15}\)Answer B
_________________
When you’re up, your friends know who you are. When you’re down, you know who your friends are.
Share some Kudos, if my posts help you. Thank you !
800Score ONLY QUANT CAT1 51, CAT2 50, CAT3 50 GMAT PREP 670 MGMAT CAT 630 KAPLAN CAT 660




Re: Last year Department Store X had a sales total for December
[#permalink]
16 Nov 2015, 13:23







