Last visit was: 26 Apr 2024, 10:30 It is currently 26 Apr 2024, 10:30

Close
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
Your Progress

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
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Close
Request Expert Reply
Confirm Cancel
SORT BY:
Kudos
Tags:
Show Tags
Hide Tags
User avatar
Manager
Manager
Joined: 21 Aug 2014
Posts: 104
Own Kudos [?]: 806 [27]
Given Kudos: 49
GMAT 1: 610 Q49 V25
GMAT 2: 730 Q50 V40
Send PM
Most Helpful Reply
Math Expert
Joined: 02 Sep 2009
Posts: 92947
Own Kudos [?]: 619203 [5]
Given Kudos: 81609
Send PM
General Discussion
Math Expert
Joined: 02 Sep 2009
Posts: 92947
Own Kudos [?]: 619203 [4]
Given Kudos: 81609
Send PM
User avatar
Manager
Manager
Joined: 21 Aug 2014
Posts: 104
Own Kudos [?]: 806 [3]
Given Kudos: 49
GMAT 1: 610 Q49 V25
GMAT 2: 730 Q50 V40
Send PM
Re: A restaurant serves 6 varieties of appetizers, 10 different entrees an [#permalink]
3
Kudos
Bunuel wrote:
Patronus wrote:
A restaurant serves 6 varieties of appetizers, 10 different entrees and 4 different desserts. In how many ways can one make a meal if one chooses an appetizer, at least one and at most two different entrees and one dessert?

A) \((6*10*4) + (6*\frac{(10*9)}{2} * 4)\)
B) 6*10*4
C) 6*10*2*4
D) 6*9*4
E) \(\frac{6*10*4}{2}\)



1 appetizer out of 6, 1 entrees out of 10, 1 dessert out of 4: \(6*10*4\);
1 appetizer out of 6, 2 entrees out of 10, 1 dessert out of 4: \(6*C^2_{10}*4=6*\frac{(10*9)}{2} * 4\).

Total = A.

Answer: A.

Thank you for the short answer Bunuel.

Can you please tell me why we should use \(\frac{(10*9)}{2}\) and not 10*9?
I solved it by thinking we have to fill 2 spots out of 10 contenders (entrees). Therefore, first spot can be filled in 10 ways and the 2nd spot in 9 ways.

Sorry, but I normally get confused with when to use Combinations and Permutations. Can you please clarify?
RSM Erasmus Moderator
Joined: 26 Mar 2013
Posts: 2461
Own Kudos [?]: 1360 [0]
Given Kudos: 641
Concentration: Operations, Strategy
Schools: Erasmus (II)
Send PM
A restaurant serves 6 varieties of appetizers, 10 different entrees an [#permalink]
Bunuel wrote:
Patronus wrote:
A restaurant serves 6 varieties of appetizers, 10 different entrees and 4 different desserts. In how many ways can one make a meal if one chooses an appetizer, at least one and at most two different entrees and one dessert?

A) \((6*10*4) + (6*\frac{(10*9)}{2} * 4)\)
B) 6*10*4
C) 6*10*2*4
D) 6*9*4
E) \(\frac{6*10*4}{2}\)



1 appetizer out of 6, 1 entrees out of 10, 1 dessert out of 4: \(6*10*4\);
1 appetizer out of 6, 2 entrees out of 10, 1 dessert out of 4: \(6*C^2_{10}*4=6*\frac{(10*9)}{2} * 4\).


Answer: A.


Hi Bunnel,

Why is there (+) in choice A? what does it mean? what not multiplication sign (*)?

Thanks
Math Expert
Joined: 02 Sep 2009
Posts: 92947
Own Kudos [?]: 619203 [0]
Given Kudos: 81609
Send PM
Re: A restaurant serves 6 varieties of appetizers, 10 different entrees an [#permalink]
Expert Reply
Mo2men wrote:
Bunuel wrote:
Patronus wrote:
A restaurant serves 6 varieties of appetizers, 10 different entrees and 4 different desserts. In how many ways can one make a meal if one chooses an appetizer, at least one and at most two different entrees and one dessert?

A) \((6*10*4) + (6*\frac{(10*9)}{2} * 4)\)
B) 6*10*4
C) 6*10*2*4
D) 6*9*4
E) \(\frac{6*10*4}{2}\)



1 appetizer out of 6, 1 entrees out of 10, 1 dessert out of 4: \(6*10*4\);
1 appetizer out of 6, 2 entrees out of 10, 1 dessert out of 4: \(6*C^2_{10}*4=6*\frac{(10*9)}{2} * 4\).


Answer: A.


Hi Bunnel,

Why is there (+) in choice A? what does it mean? what not multiplication sign (*)?

Thanks


Principle of Multiplication
If an operation can be performed in ‘m’ ways and when it has been performed in any of these ways, a second operation that can be performed in ‘n’ ways then these two operations can be performed one after the other in ‘m*n’ ways.

Principle of Addition
If an operation can be performed in ‘m’ different ways and another operation in ‘n’ different ways then either of these two operations can be performed in ‘m+n’ ways (provided only one has to be done).
Director
Director
Joined: 12 Nov 2016
Posts: 569
Own Kudos [?]: 118 [0]
Given Kudos: 167
Location: United States
Schools: Yale '18
GMAT 1: 650 Q43 V37
GRE 1: Q157 V158
GPA: 2.66
Send PM
Re: A restaurant serves 6 varieties of appetizers, 10 different entrees an [#permalink]
Patronus wrote:
A restaurant serves 6 varieties of appetizers, 10 different entrees and 4 different desserts. In how many ways can one make a meal if one chooses an appetizer, at least one and at most two different entrees and one dessert?

A) \((6*10*4) + (6*\frac{(10*9)}{2} * 4)\)
B) 6*10*4
C) 6*10*2*4
D) 6*9*4
E) \(\frac{6*10*4}{2}\)


There's two basic scenarios

6c1 x 10c1 x 4c1 = [6 x 10 x 4]

6c1 x 10c2 x 4c1 = [6 x 45 x 4]

Account for both possibilities hence
How many possibilities with 10c1 + how many possibilities with 10c2
[6 x 10 x 4] + [6 x 45 x 4]

A
User avatar
Non-Human User
Joined: 09 Sep 2013
Posts: 32688
Own Kudos [?]: 822 [0]
Given Kudos: 0
Send PM
Re: A restaurant serves 6 varieties of appetizers, 10 different entrees an [#permalink]
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 Club Bot
Re: A restaurant serves 6 varieties of appetizers, 10 different entrees an [#permalink]
Moderators:
Math Expert
92945 posts
Senior Moderator - Masters Forum
3137 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne