Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 24 May 2016, 21:14

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# The four members of a jazz quartet all play in different rhy

Author Message
TAGS:

### Hide Tags

Current Student
Status: Up again.
Joined: 31 Oct 2010
Posts: 541
Concentration: Strategy, Operations
GMAT 1: 710 Q48 V40
GMAT 2: 740 Q49 V42
Followers: 18

Kudos [?]: 270 [1] , given: 75

The four members of a jazz quartet all play in different rhy [#permalink]

### Show Tags

21 Feb 2011, 07:43
1
KUDOS
1
This post was
BOOKMARKED
00:00

Difficulty:

95% (hard)

Question Stats:

42% (02:10) correct 58% (01:51) wrong based on 125 sessions

### HideShow timer Statistics

The four members of a jazz quartet all play in different rhythms. The pianist plays in 9/8 time, meaning that his downbeats occur every 9/8 of a measure of time. Meanwhile, the saxophonist plays in 7/4 time, the harpist in 5/8 time, and the drummer in plain old 4/4 time (all with respect to the same measure of time as the pianist). If all four musicians start a song together on the same downbeat, how many measures later will all their downbeats occur simultaneously?

(A) 315
(B) 630
(C) 1,260
(D) 2,520
(E) 5,040
[Reveal] Spoiler: OA

_________________

My GMAT debrief: from-620-to-710-my-gmat-journey-114437.html

Current Student
Status: Up again.
Joined: 31 Oct 2010
Posts: 541
Concentration: Strategy, Operations
GMAT 1: 710 Q48 V40
GMAT 2: 740 Q49 V42
Followers: 18

Kudos [?]: 270 [3] , given: 75

### Show Tags

21 Feb 2011, 08:13
3
KUDOS
2
This post was
BOOKMARKED
Here's my take on this problem:

This problem basically wants us to calculate the LCM of all the numbers. Since all the beat timings are in fraction, here's a little trick that will help solve the problem quicker.

LCM (fractions)=LCM of all numerators/HCF of all denominators

$$LCM ($$$$\frac{x1}{y1}$$ $$,$$$$\frac{x2}{y2}$$$$,$$ $$\frac{x3}{y3}$$ $$,$$ $$\frac{x4}{y4}$$$$)$$= $$\frac{LCM (x1 , x2 , x3 , x4)}{HCF (y1 , y2 , y3 , y4)}$$

$$Therefore,$$ $$LCM$$ $$(\frac{9}{8}$$ $$, \frac{7}{4}, \frac{5}{8}, \frac{4}{4})$$ = $$\frac{LCM (9,7,5,4)}{HCF (8,4,8,4)}$$$$=$$ $$\frac{(9*7*5*4)}{(4)}$$$$= 315$$.

A note: To find HCF of given fractions, we can manipulate the above formula just a little:

HCF(fractions)= HCF of all numerators/LCM of all denominators.

$$HCF($$$$(\frac{x1}{y1}$$ $$,$$$$\frac{x2}{y2}$$$$,$$ $$\frac{x3}{y3}$$ $$,$$ $$\frac{x4}{y4}$$)= $$\frac{HCF (x1 , x2 , x3 , x4)}{LCM (y1 , y2 , y3 , y4)}$$
_________________

My GMAT debrief: from-620-to-710-my-gmat-journey-114437.html

Intern
Joined: 23 Feb 2011
Posts: 1
Followers: 0

Kudos [?]: 1 [0], given: 0

### Show Tags

23 Feb 2011, 14:44
1
This post was
BOOKMARKED
This problem seems to be flawed and should be reworked IMHO. For starters 315 measures of 9/8 equals 2835 half beats (1/8) so it is not a multiple of any n of measures in 4/4 or any other full beat based time signature which at the very least would require an even number of half beats. I think the problem should also be specific as to the time signature of the measures we a to count. The wording implies 9/8 (which doesn't work) but the solution seems to be using 4/4 (not sure here).

Posted from GMAT ToolKit
Manager
Joined: 07 Jun 2010
Posts: 86
Followers: 1

Kudos [?]: 28 [0], given: 0

### Show Tags

23 Feb 2011, 21:49
Where is the source for this? I think it assumes too much knowledge. What is a measure? Downbeat?
Current Student
Status: Up again.
Joined: 31 Oct 2010
Posts: 541
Concentration: Strategy, Operations
GMAT 1: 710 Q48 V40
GMAT 2: 740 Q49 V42
Followers: 18

Kudos [?]: 270 [0], given: 75

### Show Tags

24 Feb 2011, 21:39
Philmess wrote:
This problem seems to be flawed and should be reworked IMHO. For starters 315 measures of 9/8 equals 2835 half beats (1/8) so it is not a multiple of any n of measures in 4/4 or any other full beat based time signature which at the very least would require an even number of half beats. I think the problem should also be specific as to the time signature of the measures we a to count. The wording implies 9/8 (which doesn't work) but the solution seems to be using 4/4 (not sure here).

Posted from GMAT ToolKit

Actually, we dont really need to know the definitions of the music terms. Neither is it important to know whether the definitions are correct. We just need to find out what the question asks us to do ie, find out the LCM of the different timings. Only thing is that we need to deal with fractions, which could make things a little trickier. The same concept can be tested in an easier way, not involving complex terms or even fractions:

The 3 bells in a temple toll at an interval us 3,5 and 10 minutes respectively. Suppose today all three bells will toll at 9 am, at what time will the three bells toll together next?

So your approach here will be to take the LCM of the intervals, convert it into hours, add it to 9 and you have your answer.
In the original problem, the approach is the same. Only thing is that since it involves fractions, you have to apply your knowledge just a little bit more.
_________________

My GMAT debrief: from-620-to-710-my-gmat-journey-114437.html

GMAT Club Legend
Joined: 09 Sep 2013
Posts: 9614
Followers: 465

Kudos [?]: 120 [0], given: 0

### Show Tags

22 Dec 2013, 00:34
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 Legend
Joined: 09 Sep 2013
Posts: 9614
Followers: 465

Kudos [?]: 120 [0], given: 0

Re: The four members of a jazz quartet all play in different rhy [#permalink]

### Show Tags

14 Feb 2015, 19:09
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.
_________________
Intern
Joined: 16 Sep 2015
Posts: 4
Followers: 0

Kudos [?]: 0 [0], given: 2

Re: The four members of a jazz quartet all play in different rhy [#permalink]

### Show Tags

23 Nov 2015, 11:35
This is a VERY bad question.

I have to pitch in on this one.... The question is using musical terms that do not correspond to what it wants you to answer. In this one maybe not knowing about music making it easier to answer the question as you will think they are asking LCM. Right off the bat this is wrong because it wrongly asks for measure, whereas the answer is talking about beats and making an assumption that time signatures in 4 and in 8 can be treated equally.

Let's use a simple example: 3 players, 3 time signatures. 3/4, 4/4 and 12/8. By the reasoning above, they would play together on the 38th measure (which we now know is wrong, see above). If we take 3/4 as the driving rhythm as per the explanation above, they actually play together on the 13th beat, not the 12th. Now, lets draw it up("q" stands for quarter note and "e"for eight note):

Time Signature: 3/4
Measure 1 2 3 4 5
Beat 1 2 3 4 5 6 7 8 9 10 11 12 13
q q q q q q q q q q q q q

Time Signature: 4/4
Measure 1 2 3 4
Beat 1 2 3 4 5 6 7 8 9 10 11 12 13
q q q q q q q q q q q q q

Time Signature: 12/8
Measure 1 2 3
Beat 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1
e e e e e e e e e e e e e e e e e e e e e e e e e

Cheers....

Sorry about the formatting. I have no idea how to make it stay in table format.
Re: The four members of a jazz quartet all play in different rhy   [#permalink] 23 Nov 2015, 11:35
Similar topics Replies Last post
Similar
Topics:
In a sports club with 30 members, 17 play badminton and 19 play tennis 5 12 May 2016, 01:59
4 Four contestants representing four different countries advance to the 8 08 Dec 2014, 06:21
37 Four staff members at a certain company worked on a project. 12 08 Oct 2012, 01:47
10 Four staff members at a certain company worked on a project 12 27 Feb 2012, 10:03
1 Four staff members at a certain company worked on a project. 1 12 Aug 2011, 13:15
Display posts from previous: Sort by