GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 23 Oct 2019, 11:11

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

On a certain airline, customers are assigned a row number when they pu

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Find Similar Topics 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58464
On a certain airline, customers are assigned a row number when they pu  [#permalink]

Show Tags

New post 06 Mar 2017, 03:56
00:00
A
B
C
D
E

Difficulty:

  55% (hard)

Question Stats:

58% (01:44) correct 42% (01:47) wrong based on 123 sessions

HideShow timer Statistics

On a certain airline, customers are assigned a row number when they purchase their ticket, but the four seats within the row are first come, first served during boarding. If Karen and Georgia end up with random seats in the same row on a sold-out flight, what is the probability that they sit next to each other?

A. 25%
B. 40%
C. 50%
D. 75%
E. 80%

_________________
Intern
Intern
avatar
B
Joined: 09 Sep 2016
Posts: 35
Location: Georgia
Concentration: Finance, International Business
GPA: 3.75
WE: Analyst (Investment Banking)
Re: On a certain airline, customers are assigned a row number when they pu  [#permalink]

Show Tags

New post 06 Mar 2017, 07:03
i dont know if i am correct but here how i would do it:
probability of karen sitting on the edge of the row is 2/4 = 1/2 , if karen sits on the edge there is one possibility for georgia to sit besides her so probability would be 1/3 for here. together 1/2*1/3=1/6
the probability of karen sitting mid is 1/2 and probability of georgia sitting besides her is 2/3 - so together 1/2*2/3=2/6

together 1/6 + 2/6 = 3/6 = 50%
Chat Moderator
User avatar
S
Joined: 07 Mar 2016
Posts: 49
On a certain airline, customers are assigned a row number when they pu  [#permalink]

Show Tags

New post Updated on: 06 Mar 2017, 08:54
2
Easiest way to solve, for myself atleast, is to illustrate: let "x" be the customers and "o" be the open seats

x-x-o-o
o-x-x-o
o-o-x-x
x-o-x-o
o-x-o-x
x-o-o-x

3 ways that the pair can sit together out of a total of 6 arrangements. Simply divide and the result is 50%.
_________________
...once in a while you get shown the light, in the strangest of places if you look at it right...

Originally posted by emockus on 06 Mar 2017, 07:35.
Last edited by emockus on 06 Mar 2017, 08:54, edited 2 times in total.
Intern
Intern
avatar
Joined: 26 Feb 2017
Posts: 3
Re: On a certain airline, customers are assigned a row number when they pu  [#permalink]

Show Tags

New post 06 Mar 2017, 08:22
There is 4C2 ways Karen and Georgia can sit in the row.
There is 3C1 ways Karen and Georgia can sit togheter in the row (Imagine Karen and Georgia as a single unit, so there are just 3 other seats to ocuppy).

(Farovable outcomes)/(total outcomes) = 3C1/4C2 = 3/6 = 50%
Target Test Prep Representative
User avatar
D
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 8137
Location: United States (CA)
Re: On a certain airline, customers are assigned a row number when they pu  [#permalink]

Show Tags

New post 07 Mar 2017, 17:19
2
2
Bunuel wrote:
On a certain airline, customers are assigned a row number when they purchase their ticket, but the four seats within the row are first come, first served during boarding. If Karen and Georgia end up with random seats in the same row on a sold-out flight, what is the probability that they sit next to each other?

A. 25%
B. 40%
C. 50%
D. 75%
E. 80%


In a row of 4 seats, there are 4! = 24 sitting arrangements for 4 people. Now let’s find the number of ways that Karen (K) and Georgia (G) will be sitting next to each other. Let’s designate the other two passengers as A and B, and they are sitting in the same row as Karen and Georgia. The arrangement could be as follows:

[KG]-[A]-[B]

Since K and G are sitting next to each other, we can count [KG] as one person, such that there are 3 people sitting in the same row, and thus the number of ways to arrange those 3 people is 3! = 6. However, since we can arrange KG in 2! ways (KG or GK), the number of ways to arrange the “3 people” is actually 2 x 6 = 12. Thus, the probability that Karen and Georgia are sitting next to each other is 12/24 = 1/2 = 50%.

Answer: C
_________________

Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
TTP - Target Test Prep Logo
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

Intern
Intern
avatar
B
Joined: 16 Jan 2017
Posts: 5
Re: On a certain airline, customers are assigned a row number when they pu  [#permalink]

Show Tags

New post 10 Mar 2017, 04:50
How can there be 12 different ways that they sit next to each other?
I even drew it out and still dont get it.

1 / 2 / 3 / 4
k / g / x /x
g/ k / x /x
x / k / g / x
x/ g / k / x
x / x / k / g
x / x / g / k

for me there would be 6 different ways. out of 24 possible arrangements.
therefore I would say answer A.

Please tell me where my mistake lies.
Intern
Intern
avatar
B
Joined: 15 Sep 2015
Posts: 16
Re: On a certain airline, customers are assigned a row number when they pu  [#permalink]

Show Tags

New post 10 Mar 2017, 09:27
1
Consider K & G to be one group as they will be sitting next to each other. Therefore, the total arrangements among 3 seats (K&G is one & other two) will be 3!x2!, since within the group, K & G can sit in two ways. Divide by total no of possibilities - 4!. Therefore ans is 50%
Director
Director
User avatar
V
Joined: 27 May 2012
Posts: 904
On a certain airline, customers are assigned a row number when they pu  [#permalink]

Show Tags

New post 20 Mar 2018, 06:46
Bunuel wrote:
On a certain airline, customers are assigned a row number when they purchase their ticket, but the four seats within the row are first come, first served during boarding. If Karen and Georgia end up with random seats in the same row on a sold-out flight, what is the probability that they sit next to each other?

A. 25%
B. 40%
C. 50%
D. 75%
E. 80%



Consider KG as one unit hence A{KG}B where A and B are the other two passengers hence total ways to arrange them is \(3_C_1\) = 3
A and B can be arranged in \(2_C_
{1}\) =2 ways
KG themselves can be arranged in \(2_C_{1}\) =2 ways
Hence total favorable cases that they can be arranged in are 3*2*2 =12
Total arrangements are 4*3*2*1 =24
hence probability = \(\frac{12}{24}\) = 50%
_________________
- Stne
Intern
Intern
avatar
B
Joined: 03 Jun 2019
Posts: 22
Re: On a certain airline, customers are assigned a row number when they pu  [#permalink]

Show Tags

New post 29 Jun 2019, 08:18
Bunuel wrote:
On a certain airline, customers are assigned a row number when they purchase their ticket, but the four seats within the row are first come, first served during boarding. If Karen and Georgia end up with random seats in the same row on a sold-out flight, what is the probability that they sit next to each other?

A. 25%
B. 40%
C. 50%
D. 75%
E. 80%




Can anyone please help in understanding the problem which i had some difficulties with.

The problem says 4 random seats are on first come first serve basis in a row, it is only mentioned that K & G end up in same row and not said that in the same 4 random
seats assigned on FCFS basis. So isn't there any probability for them to end up in seats other than the 4 seats. So they may come first and sits next in that 4 seats
and may come and six next to one other in the remaining seats.

This thought really caught me, can any please help me get out of this please. :)
Director
Director
User avatar
V
Joined: 27 May 2012
Posts: 904
On a certain airline, customers are assigned a row number when they pu  [#permalink]

Show Tags

New post 29 Jun 2019, 09:10
1
Sreeragc wrote:
Bunuel wrote:
On a certain airline, customers are assigned a row number when they purchase their ticket, but the four seats within the row are first come, first served during boarding. If Karen and Georgia end up with random seats in the same row on a sold-out flight, what is the probability that they sit next to each other?

A. 25%
B. 40%
C. 50%
D. 75%
E. 80%




Can anyone please help in understanding the problem which i had some difficulties with.

The problem says 4 random seats are on first come first serve basis in a row, it is only mentioned that K & G end up in same row and not said that in the same 4 random
seats assigned on FCFS basis. So isn't there any probability for them to end up in seats other than the 4 seats. So they may come first and sits next in that 4 seats
and may come and six next to one other in the remaining seats.

This thought really caught me, can any please help me get out of this please. :)



Hi Sreeragc,

Thank you for sharing your query:

May be this will help
Passengers are only assigned row numbers they are not assigned seat numbers.
K and G receive the same row number, hence they will be in the same row, doesn't matter which row they will be in, question is asking probability of them sitting next to each other, it's already given they will be in the same row.

Question is not asking , find probability of them sitting in the same row and then sit next to each other.
It's already given they are given the same row number.Don't think of choosing a row from various rows, that is not being asked.

Let me know if anything is still unclear.
_________________
- Stne
Intern
Intern
avatar
B
Joined: 03 Jun 2019
Posts: 22
Re: On a certain airline, customers are assigned a row number when they pu  [#permalink]

Show Tags

New post 29 Jun 2019, 10:56
stne wrote:
Sreeragc wrote:
Bunuel wrote:
On a certain airline, customers are assigned a row number when they purchase their ticket, but the four seats within the row are first come, first served during boarding. If Karen and Georgia end up with random seats in the same row on a sold-out flight, what is the probability that they sit next to each other?

A. 25%
B. 40%
C. 50%
D. 75%
E. 80%




Can anyone please help in understanding the problem which i had some difficulties with.

The problem says 4 random seats are on first come first serve basis in a row, it is only mentioned that K & G end up in same row and not said that in the same 4 random
seats assigned on FCFS basis. So isn't there any probability for them to end up in seats other than the 4 seats. So they may come first and sits next in that 4 seats
and may come and six next to one other in the remaining seats.

This thought really caught me, can any please help me get out of this please. :)



Hi Sreeragc,

Thank you for sharing your query:

May be this will help
Passengers are only assigned row numbers they are not assigned seat numbers.
K and G receive the same row number, hence they will be in the same row, doesn't matter which row they will be in, question is asking probability of them sitting next to each other, it's already given they will be in the same row.

Question is not asking , find probability of them sitting in the same row and then sit next to each other.
It's already given they are given the same row number.Don't think of choosing a row from various rows, that is not being asked.

Let me know if anything is still unclear.



Thank you stne, that was a great help, four seats within the row was the real point i was missing. Now i got it, each row only has four sets.
Now its good to go with the rest. Thanks again. :thumbup:
GMAT Club Bot
Re: On a certain airline, customers are assigned a row number when they pu   [#permalink] 29 Jun 2019, 10:56
Display posts from previous: Sort by

On a certain airline, customers are assigned a row number when they pu

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  





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