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

It is currently 14 Aug 2018, 10:11

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

2/3 of all the people who attended a certain party arrived by 8:00 PM.

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

Hide Tags

Current Student
User avatar
Joined: 12 Aug 2015
Posts: 291
Concentration: General Management, Operations
GMAT 1: 640 Q40 V37
GMAT 2: 650 Q43 V36
GMAT 3: 600 Q47 V27
GPA: 3.3
WE: Management Consulting (Consulting)
2/3 of all the people who attended a certain party arrived by 8:00 PM.  [#permalink]

Show Tags

New post 10 Nov 2015, 12:00
1
11
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

59% (01:08) correct 41% (01:03) wrong based on 399 sessions

HideShow timer Statistics

2/3 of all the people who attended a certain party arrived by 8:00 PM. How many people arrived by 8:00 PM?

(1) 9 people arrived after 9:00 PM.

(2) 21 people arrived between 8:00 PM and 9:00 PM, and by 9:00 PM 90% of all the people who attended the party had arrived.

_________________

KUDO me plenty

Most Helpful Expert Reply
CEO
CEO
User avatar
P
Joined: 12 Sep 2015
Posts: 2699
Location: Canada
Re: 2/3 of all the people who attended a certain party arrived by 8:00 PM.  [#permalink]

Show Tags

New post 10 Nov 2015, 16:53
7
1
shasadou wrote:
2/3 of all the people who attended a certain party arrived by 8:00 PM. How many people arrived by 8:00 PM?

(1) 9 people arrived after 9:00 PM.

(2) 21 people arrived between 8:00 PM and 9:00 PM, and by 9:00 PM 90% of all the people who attended the party had arrived.


Target question: How many people arrived by 8:00 PM?

Given: 2/3 of all the people who attended a certain party arrived by 8:00 PM

IMPORTANT: To answer the target question, we need to know the TOTAL number of people who attended the party.

Statement 1: 9 people arrived after 9:00 PM
This doesn't help because we don't know how many people arrived between 8pm and 9pm. During this period it's possible that no one arrived, or it's possible that millions of people arrived.
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: 21 people arrived between 8:00 PM and 9:00 PM, and by 9:00 PM 90% of all the people who attended the party had arrived.
Let T = TOTAL number of people who attended the party
Given: 2/3 of all the people who attended a certain party arrived by 8:00 PM
So, we can say that (2/3)T = number of people who arrived by 8:00 PM

21 people arrived between 8:00 PM and 9:00 PM.....
So, at 9pm, the number of people at the party = (2/3)T + 21

....by 9:00 PM 90% of all the people who attended the party had arrived.
In other words, at 9pm, the number of people at the party = (9/10)T

So, we have two different ways to express the number of people at the party at 9pm.
We can write: (2/3)T + 21 = (9/10)T

At this point, we need only recognize that we COULD solve this equation and find one unique value of T, which means we COULD determine how many people arrived by 8:00 PM
Since we COULD answer the target question with certainty, statement 2 is SUFFICIENT

Answer = B

Cheers,
Brent
_________________

Brent Hanneson – Founder of gmatprepnow.com

Image

General Discussion
Intern
Intern
avatar
Joined: 18 Apr 2017
Posts: 1
Re: 2/3 of all the people who attended a certain party arrived by 8:00 PM.  [#permalink]

Show Tags

New post 15 May 2017, 03:31
Hi - I have a doubt in the first statement. As it is give that 2/3 of the people who attended the party arrive by 8 pm and 9 after 9 pm, then can't we say that the 9 who arrived later were 1/3 as 2/3 are already in the party. Therefore, by this total number of people are 27. Please suggest
Manager
Manager
avatar
B
Joined: 11 Sep 2016
Posts: 61
Location: India
GMAT 1: 710 Q47 V40
GPA: 3
WE: Sales (Manufacturing)
2/3 of all the people who attended a certain party arrived by 8:00 PM.  [#permalink]

Show Tags

New post 21 May 2017, 03:45
Isushant wrote:
Hi - I have a doubt in the first statement. As it is give that 2/3 of the people who attended the party arrive by 8 pm and 9 after 9 pm, then can't we say that the 9 who arrived later were 1/3 as 2/3 are already in the party. Therefore, by this total number of people are 27. Please suggest

No you cannot say that since we do not know how many people arrived between 8:00 PM and 9:00 PM. Assume if 3 people had arrived between 8-9 PM then the \(\frac{1}{3}\) of total number of attendees = 9+3 = 12. only If you had known somehow that 0 people had arrived between 8-9 PM then and only then you could conclude that \(\frac{1}{3}\) of total no. of attendees = 9+0=9

Hope this is clear




Please hit +1 Kudos if you find this helpful
Intern
Intern
avatar
B
Joined: 17 Nov 2016
Posts: 26
Re: 2/3 of all the people who attended a certain party arrived by 8:00 PM.  [#permalink]

Show Tags

New post 26 Aug 2017, 11:19
I got confused with the wording of "21 people arrived between 8:00 PM and 9:00 PM"

Can't between 8:00 and 9:00 include those who reached by 8:00?

Thanks
Re: 2/3 of all the people who attended a certain party arrived by 8:00 PM. &nbs [#permalink] 26 Aug 2017, 11:19
Display posts from previous: Sort by

2/3 of all the people who attended a certain party arrived by 8:00 PM.

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

Events & Promotions

PREV
NEXT


GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

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

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.