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.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

Re: Theater M has 25 rows with 27 seats in each row. How many of [#permalink]

Show Tags

20 Jun 2008, 02:38

1

This post received KUDOS

quantum wrote:

Theater M has 25 rows with 27 seats in each row. How many of the seats were occupied during a certain show? (1) During the show, there was an average (arithmetic mean) of 10 unoccupied seats per row for the front 20 rows. (2) During the show, there was an average (arithmetic mean) of 20 unoccupied seats per row for the back 15 rows.

Hope you like that one!

1 not suff, because you have info. only about the front 20 rows, the back 5 rows, you dont know whether it is occupied?

Re: Theater M has 25 rows with 27 seats in each row. How many of [#permalink]

Show Tags

20 Jun 2008, 02:49

Yes C cannot be the case - mathematically: Let 0-10 be o1 and v1 for occupied & Vacant respectively similary for 10-20 o2 & v2 and the 20-25 as o3 & v3

From Q stem: o1+v1=270, o2+v2=270 & o3+v3=135 Target: To find o1+o2+o3

Now frm st 1: v1+v2=200 -------insuffi

St2: v2+v3=300 ---Insuffi

St1+2: We end up with eqs: o1+o2=270 & o2+o3=105 ---- no way can we find the target hence E.

Re: Theater M has 25 rows with 27 seats in each row. How many of [#permalink]

Show Tags

20 Jun 2008, 03:03

quantum wrote:

But can someone explain in details why C is wrong?

Oh, just think that you can figure out!

C is combine 1 and 2. You see the intersection between group1(statement1) and group2(statement2) has NOT-fixed number of seats unoccupied. You can be sure only that the number of rows in the intersection is 5 rows, but statement1 say average per row is 10 unoccupied and statement2 says everage per row is 20 unoccupied. So the total number of seats unoccupied in 5 rows in the intersection can be 50 or 100 seats.

Re: Theater M has 25 rows with 27 seats in each row. How many of [#permalink]

Show Tags

20 Jun 2008, 14:02

9

This post received KUDOS

3

This post was BOOKMARKED

quantum wrote:

Theater M has 25 rows with 27 seats in each row. How many of the seats were occupied during a certain show? (1) During the show, there was an average (arithmetic mean) of 10 unoccupied seats per row for the front 20 rows. (2) During the show, there was an average (arithmetic mean) of 20 unoccupied seats per row for the back 15 rows.

Hope you like that one!

E

Attachments

theater.gif [ 9.82 KiB | Viewed 10747 times ]

_________________

Factorials were someone's attempt to make math look exciting!!!

Re: Theater M has 25 rows with 27 seats in each row. How many of [#permalink]

Show Tags

21 Jun 2008, 02:17

1

This post was BOOKMARKED

quantum wrote:

Theater M has 25 rows with 27 seats in each row. How many of the seats were occupied during a certain show? (1) During the show, there was an average (arithmetic mean) of 10 unoccupied seats per row for the front 20 rows. (2) During the show, there was an average (arithmetic mean) of 20 unoccupied seats per row for the back 15 rows.

Hope you like that one!

Stem :- Total number is seats = 25 * 27 = 675 To find :- No of seats occupied 'x'.

Option1 ) Avg of 10 unoccupied seats in the front row Number of seats unocupied in the front 20 rows = 200 seats. Total number of occupied seats = 675 -200 = 475 . SUFF

Option 2 ) Avg of 10 unoccupied seats in the back 15 rows:- 20 Total number of seats unoccupied = 20 *15 = 300 Total number of occupied seats = 675 -300 = 375 . SUFF

Theater M has 25 rows with 27 seats in each row. How many of [#permalink]

Show Tags

08 Jan 2010, 14:23

1

This post was BOOKMARKED

Theater M has 25 rows with 27 seats in each row. How many of the seats were occupied during a certain show?

(1) During the show, there was an average (arithmetic mean) of 10 unoccupied seats per row for the front 20 rows. (2) During the show, there was an average (arithmetic mean) of 20 unoccupied seats per row for the back 15 rows.

Re: Theater M has 25 rows with 27 seats in each row. [#permalink]

Show Tags

26 Apr 2013, 22:53

1

This post received KUDOS

Theater M has 25 rows with 27 seats in each row. How many of the seats were occupied during a certain show?

(1) During the show, there was an average (arithmetic mean) of 10 unoccupied seats per row for the front 20 rows. Clearly not sufficient, no info about other rows

(2) During the show, there was an average (arithmetic mean) of 20 unoccupied seats per row for the back 15 rows. Clearly not sufficient, no info about other rows

1+2)With 1 we know that there are 200 unoccupied in the first 20 rows, with 2 we know that there are 300 unoccupied in the last 15 rows. Because we don't know how many seats there are in the common part (rows 10-20) both statements are still not sufficient. E

Hope it's clear, let me know
_________________

It is beyond a doubt that all our knowledge that begins with experience.

Re: Theater M has 25 rows with 27 seats in each row. How many of [#permalink]

Show Tags

11 Oct 2013, 06:32

1

This post was BOOKMARKED

sagarsabnis wrote:

Theater M has 25 rows with 27 seats in each row. How many of the seats were occupied during a certain show?

(1) During the show, there was an average (arithmetic mean) of 10 unoccupied seats per row for the front 20 rows. (2) During the show, there was an average (arithmetic mean) of 20 unoccupied seats per row for the back 15 rows.

Statement 1 - Clearly insfficient, we only have information about 20 rows Statement 2- Same here, we are missing information on other rows

Now both (1) and (2) together - So we have from the 1st statement that the total number of seats for the first 20 rows that were unnocupied totaled 200. And also the unnocpied for the back 15 rows were 300. But we have an overlap here between rows. If we don't have more information it will be impossible to know. Imagine a venn diagram and visualize the intersection between both. As long as you don't have the exact value for the intersection it will be impossible to know the total number of unnocupied seats and hence know what the occupied seats are.

Re: Theater M has 25 rows with 27 seats in each row. How many of [#permalink]

Show Tags

22 Nov 2014, 22:50

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.
_________________

Re: Theater M has 25 rows with 27 seats in each row. How many of [#permalink]

Show Tags

17 Jan 2015, 13:09

1

This post received KUDOS

E

Try seeing extremes.... statements didnt concretize the seating pattern so

divide rows into 3 parts first 10 + 10 + 5 rows

extreme 1: Middle set takes average of say 30 (higher side)

first 10 has average of <10 unoccupied (say 5..u can calculate actual possibility) + next 10 say abt 30 + last 5 has average of <20 unoccupied => would have a overall count on lower side

extreme 2: Middle set takes average of say 5

first 10 has average of >10 unoccupied (say 20..u can calculate actual possibility) + next 10 say abt 5 + last 5 has average of >20 unoccupied => would have a overall count on higher side

The logic is the middle set can act as cushion so we have a range of possibilities

Had their been no overlap....then we can find the total

Re: Theater M has 25 rows with 27 seats in each row. How many of [#permalink]

Show Tags

17 Jan 2015, 13:09

2

This post received KUDOS

E

Try seeing extremes.... statements didnt concretize the seating pattern so

divide rows into 3 parts first 10 + 10 + 5 rows

extreme 1: Middle set takes average of say 30 (higher side)

first 10 has average of <10 unoccupied (say 5..u can calculate actual possibility) + next 10 say abt 30 + last 5 has average of <20 unoccupied => would have a overall count on lower side

extreme 2: Middle set takes average of say 5

first 10 has average of >10 unoccupied (say 20..u can calculate actual possibility) + next 10 say abt 5 + last 5 has average of >20 unoccupied => would have a overall count on higher side

The logic is the middle set can act as cushion so we have a range of possibilities

Had their been no overlap....then we can find the total

The type of situation that this DS question is based on is relatively rare, but the most efficient way to deal with it is to think about the "extreme" possibilities in the numbers.

I assume that you recognized that each Fact was insufficient on its own (since neither Fact gives you enough information about ALL 25 rows. When combining Facts, you have to recognize that there's an "overlap" - the "front 20 rows" mentioned in Fact 1 and the "back 15 rows" mentioned in Fact 2 include a series of 10 rows that are a part of BOTH calculations (remember that there are only 25 rows in TOTAL).

It's in those 10 overlapping rows that you can greatly impact the calculations. What if ALL of those seats were full? What if ALL of those seats were empty? In those two examples, you will find 2 different answers to the question. If you've comfortable drawing pictures and 'visualizing' the calculations, you can actually avoid most of the 'math' altogether.

Re: Theater M has 25 rows with 27 seats in each row. How many of [#permalink]

Show Tags

17 Mar 2015, 00:38

EMPOWERgmatRichC wrote:

Hi solitaryreaper,

The type of situation that this DS question is based on is relatively rare, but the most efficient way to deal with it is to think about the "extreme" possibilities in the numbers.

I assume that you recognized that each Fact was insufficient on its own (since neither Fact gives you enough information about ALL 25 rows. When combining Facts, you have to recognize that there's an "overlap" - the "front 20 rows" mentioned in Fact 1 and the "back 15 rows" mentioned in Fact 2 include a series of 10 rows that are a part of BOTH calculations (remember that there are only 25 rows in TOTAL).

It's in those 10 overlapping rows that you can greatly impact the calculations. What if ALL of those seats were full? What if ALL of those seats were empty? In those two examples, you will find 2 different answers to the question. If you've comfortable drawing pictures and 'visualizing' the calculations, you can actually avoid most of the 'math' altogether.

GMAT assassins aren't born, they're made, Rich

Thanks Rich, that helps!

I was looking for a logical approach to tackle such problems under 2 minutes. I think it's not always fruitful to approach such problems in pure mathematical way(because one might end up loosing precious time and energy) . That's where GMAT surprise you by throwing such problems that demand for a more logical approach. IMO such problems and methodologies should be discussed in a greater number !

You've hit on an important point - knowing MORE than one way to approach questions can be quite helpful on Test Day. For most of your life, you were taught just 1 way to approach a question. When you took a test in school, you were supposed to use that 1 way and so you studied just that 1 way. On the GMAT though, many questions are designed to 'reward' a Test Taker for being is a critical thinker or pattern-matcher more than for being a mathematician. During your studies, it's important to practice more than one approach so that you have the flexibility on Test Day to decide which method is easiest/fastest.

Another thing worth noting is that you should NOT be trying to answer every Quant question within 2 minutes. The AVERAGE amount of time that you'll spend per question over the course of the entire Quant section is about 2 minutes, but your GOAL is actually to work in an efficient fashion. A question might require 1 minute or 3 minutes - and that's fine as long as you're not wasting time. If this question takes you 2.5 minutes, then that's not a problem.

Re: Theater M has 25 rows with 27 seats in each row. How many of [#permalink]

Show Tags

30 Mar 2016, 23:20

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.
_________________

After days of waiting, sharing the tension with other applicants in forums, coming up with different theories about invites patterns, and, overall, refreshing my inbox every five minutes to...

I was totally freaking out. Apparently, most of the HBS invites were already sent and I didn’t get one. However, there are still some to come out on...

In early 2012, when I was working as a biomedical researcher at the National Institutes of Health , I decided that I wanted to get an MBA and make the...