Mar 20 09:00 PM EDT  10:00 PM EDT Strategies and techniques for approaching featured GMAT topics. Wednesday, March 20th at 9 PM EDT Mar 20 07:00 AM PDT  09:00 AM PDT Join a FREE 1day workshop and learn how to ace the GMAT while keeping your fulltime job. Limited for the first 99 registrants. Mar 23 07:00 AM PDT  09:00 AM PDT Christina scored 760 by having clear (ability) milestones and a trackable plan to achieve the same. Attend this webinar to learn how to build trackable milestones that leverage your strengths to help you get to your target GMAT score.
Author 
Message 
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 53734

At a certain upscale restaurant, there just two kinds of food items: e
[#permalink]
Show Tags
17 Mar 2015, 05:55
Question Stats:
73% (03:08) correct 27% (03:12) wrong based on 88 sessions
HideShow timer Statistics



Intern
Joined: 21 Jan 2015
Posts: 21

Re: At a certain upscale restaurant, there just two kinds of food items: e
[#permalink]
Show Tags
17 Mar 2015, 07:00
It is just about resolving some equations :
X is the number of entrees Y is the number of appetizers
1) X+Y = 15 2) (30X+12Y)/15=18
1 and 2 give X=5 and Y = 10
Then next year, Z is the number of added appetizers 3) (30*5+12*(10+Z))/(15+Z)=15
I found Z = 15



SVP
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1817
Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)

Re: At a certain upscale restaurant, there just two kinds of food items: e
[#permalink]
Show Tags
17 Mar 2015, 23:17
Answer= E = 15 Let the number of entrees = x, then number of appetizers = 15x Given that \(\frac{30x + 12(15x)}{15} = 18\) Solving we get x = number of entrees = 5 & number of appetizers = 10 Say number of appetizers added = y New equation \(= \frac{30*5 + 12(10+y)}{15+y} = 15\) y = 15
_________________
Kindly press "+1 Kudos" to appreciate



Director
Joined: 07 Aug 2011
Posts: 523
Concentration: International Business, Technology

Re: At a certain upscale restaurant, there just two kinds of food items: e
[#permalink]
Show Tags
18 Mar 2015, 04:13
PareshGmat wrote: Answer= E = 15
Let the number of entrees = x, then number of appetizers = 15x
Given that \(\frac{30x + 12(15x)}{15} = 18\)
Solving we get x = number of entrees = 5 & number of appetizers = 10
Say number of appetizers added = y
New equation \(= \frac{30*5 + 12(10+y)}{15+y} = 15\)
y = 15 Hi Paresh, One question : The current price is as follows: Each entrée item costs $30, and each appetizer item costs $12. Last year the breakup was > Last year, it had a total of 15 food items on the menu, and the average price of a food item on its menu was $18. Then why are we setting up a equation which takes current prices and average prices from last year ? \(\frac{30x + 12(15x)}{15} = 18\) Thanks Lucky



Current Student
Joined: 09 Feb 2014
Posts: 39
Concentration: General Management, Operations
GPA: 3.6

Re: At a certain upscale restaurant, there just two kinds of food items: e
[#permalink]
Show Tags
18 Mar 2015, 08:29
PareshGmat wrote: Answer= E = 15
Let the number of entrees = x, then number of appetizers = 15x
Given that \(\frac{30x + 12(15x)}{15} = 18\)
Solving we get x = number of entrees = 5 & number of appetizers = 10
Say number of appetizers added = y
New equation \(= \frac{30*5 + 12(10+y)}{15+y} = 15\)
y = 15 This is pretty straightforward and I took the same approach, but it still took me over 3 minutes to work out the equations and solve. 1. Is this too long to take for this type of question? 2. Any tips to increase speed?



Math Expert
Joined: 02 Aug 2009
Posts: 7419

At a certain upscale restaurant, there just two kinds of food items: e
[#permalink]
Show Tags
18 Mar 2015, 09:26
mr7183 wrote: This is pretty straightforward and I took the same approach, but it still took me over 3 minutes to work out the equations and solve.
1. Is this too long to take for this type of question? 2. Any tips to increase speed? hi, 1. 3 minutes is slightly more and specially when you feel it is straightforward.. 2. ofcourse you need to tackle different type of Q in different ways to lower the time..  few Q are best by choosing/putting appropriate value for variable and then check the answer  few are best solved by putting the value given in choices  few through proper mathematical way... in this Q, best method is weighted average but you require to practice these.. At a certain upscale restaurant, there just two kinds of food items: entrees and appetizers. Each entrée item costs $30, and each appetizer item costs $12. Last year, it had a total of 15 food items on the menu, and the average price of a food item on its menu was $18. This year, it added more appetizer items, and the average price of a food item on its menu dropped to $15. How many appetizer items did it add this year? A. 3 B. 6 C. 9 D. 12 E. 15 first lets find initial ratio of E:A... there average values are 12 and 30 and combined average brings it to 18... so A:E=3018:1812=12:6=2:1 or A=10 and E=5 as total is 15.. let y appetizers be added so number of A=10+y.... and now combined average is 15 so A:E=3015:1512=5:1=10+y:5..... \(\frac{5}{1}=\frac{(10+y)}{5}\) 10+y=25... so y=15... ans E..
_________________
1) Absolute modulus : http://gmatclub.com/forum/absolutemodulusabetterunderstanding210849.html#p1622372 2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html 3) effects of arithmetic operations : https://gmatclub.com/forum/effectsofarithmeticoperationsonfractions269413.html 4) Base while finding % increase and % decrease : https://gmatclub.com/forum/percentageincreasedecreasewhatshouldbethedenominator287528.html
GMAT Expert



Intern
Joined: 08 Sep 2014
Posts: 17

Re: At a certain upscale restaurant, there just two kinds of food items: e
[#permalink]
Show Tags
18 Mar 2015, 10:10
The total cost of appetizers + entrees last year = $18 * 15
Let there be 'x' appetizers added this year, then total cost of food items = $15 * (15+x)
Since, cost of each appetizer is $12, we have
18*15 + 12x = 15*15 + 15x 3x = 3*15
Therefore, no. of appetizers added this year, x = 15
Answer (E)



Math Expert
Joined: 02 Sep 2009
Posts: 53734

Re: At a certain upscale restaurant, there just two kinds of food items: e
[#permalink]
Show Tags
23 Mar 2015, 04:10
Bunuel wrote: At a certain upscale restaurant, there just two kinds of food items: entrees and appetizers. Each entrée item costs $30, and each appetizer item costs $12. Last year, it had a total of 15 food items on the menu, and the average price of a food item on its menu was $18. This year, it added more appetizer items, and the average price of a food item on its menu dropped to $15. How many appetizer items did it add this year?
A. 3 B. 6 C. 9 D. 12 E. 15
Kudos for a correct solution. MAGOOSH OFFICIAL SOLUTION:Method I: using sumsFirst, last year. Let x be the number of entrees. Then (15 – x) is the number of appetizers. The sums are: entrees = 30x appetizers = (15 – x)*12 = 12*15 – 12x = 6*30 – 12x = 180 – 12x total = 15*18 = 30*9 = 270 Notice the use of the Doubling and Halving trick in the second and third lines. The two individual sums should add up to the total sum. 30x + 180 – 12x = 270 18x = 90 x = 5 They start out with 5 entrees and 10 appetizers. Let N be the number of appetizers added, so now there are 5 entrees and (10 + N) appetizers. We need to solve for N. Again, the sums: entrees = 5*30 = 150 appetizers = (10 + N)*12 = 120 + 12N total = (15 + N)*15 = 225 + 15N Again, the two individual sums should add up to the total sum. 150 + 120 + 12N = 225 + 15N 270 = 225 + 3N 45 = 3N 15 = N They added 15 more appetizers. Answer = (E) Method I was doable, but we had to solve for many values. Method II: proportional placement of the total averageOriginally, the entrée price was 30 – 18 = 12 from the total average, and the appetizer price was 18 – 12 = 6. This means there must have been twice as many appetizers as entrees. Therefore , with 15 items, there must have been 10 appetizers and 5 entrees. The number of entrees doesn’t change. The average drops to $15, so the distance from the entrée price is now 30 – 15 = 15, and the distance from the appetizer price is now 15 – 12 = 3. That’s a 5to1 ratio, which means there must be 5x as many appetizers as entrees. Since there still are 5 entrees, there must now be 25 appetizers, so 15 have been added. Answer = (E) If you know how to employ this method, it is much more elegant.
_________________
New to the Math Forum? Please read this: Ultimate GMAT Quantitative Megathread  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



Intern
Joined: 29 Sep 2015
Posts: 6

Re: At a certain upscale restaurant, there just two kinds of food items: e
[#permalink]
Show Tags
21 Dec 2015, 02:35
I directly solved for X the number of appetizers added. We know that [(18 x 15) + 12 x X ] / (15 + X) = 15 We can solved directly for X without caring what was the number of appetizers last year.



Current Student
Joined: 02 Jun 2015
Posts: 78
Location: Brazil
Concentration: Entrepreneurship, General Management
GPA: 3.3

Re: At a certain upscale restaurant, there just two kinds of food items: e
[#permalink]
Show Tags
21 Dec 2015, 04:15
Total of last year = 15*18 = 270
this year > (270 + 12x)/(15+x) = 15
x= 15



NonHuman User
Joined: 09 Sep 2013
Posts: 10152

Re: At a certain upscale restaurant, there just two kinds of food items: e
[#permalink]
Show Tags
07 Mar 2019, 19:04
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.
_________________
GMAT Books  GMAT Club Tests  Best Prices on GMAT Courses  GMAT Mobile App  Math Resources  Verbal Resources




Re: At a certain upscale restaurant, there just two kinds of food items: e
[#permalink]
07 Mar 2019, 19:04






