It is currently 18 Mar 2018, 23:51

### 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

# 3 hard problems

Author Message
CEO
Joined: 17 Nov 2007
Posts: 3525
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40

### Show Tags

14 Feb 2009, 23:58
tusharvk wrote:
I am not sure I understood the problem though. If they are asking us to find all the five integers so that the sum can be inferred, we certainly need more equations (5 equns to solve 5 unknowns).
If we are just to find what the sum is equal to then just 1 is sufficient.

How do I distinguish this? If faced with this question (without the subject line saying hard problems), I would definitely have answered E because we need 5 equations.

I read problem slowly and at least twice, monitoring "red flags" and other special words. It is typical for GMAT to trick us using words like "integer, even, distinct nonzero, consecutive". Here, the question begins: "What is the sum of .....?". By the way, I think the answer is E: sum could be 8 or 9.

matematikconsultant wrote:
But sum of 4 the least from 5 in ours case always < 5 and ........?

Sorry, don't get it. By the way, where did you find such nice problems?
_________________

HOT! GMAT TOOLKIT 2 (iOS) / GMAT TOOLKIT (Android) - The OFFICIAL GMAT CLUB PREP APP, a must-have app especially if you aim at 700+ | PrepGame

Intern
Joined: 13 Feb 2009
Posts: 21

### Show Tags

15 Feb 2009, 05:26
Walker!
Sorry, not sum. Product. If f is largest, then m/f <1, n/f<1, etc and m/f +n/f + p/f +K/f +1 = mnpk ----->
mnpk<5.
As for problems, I am a trainer on GMAT and I have thought up them
CEO
Joined: 17 Nov 2007
Posts: 3525
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40

### Show Tags

15 Feb 2009, 06:55
Cool!

You may add your signature to each post with information that you are a tutor. So, somebody may contact you if he or she is interesting in your services. Of course, if it is appropriate for you. Just a suggestion...
_________________

HOT! GMAT TOOLKIT 2 (iOS) / GMAT TOOLKIT (Android) - The OFFICIAL GMAT CLUB PREP APP, a must-have app especially if you aim at 700+ | PrepGame

Intern
Joined: 13 Feb 2009
Posts: 21

### Show Tags

15 Feb 2009, 07:56
Walker!
CEO
Joined: 17 Nov 2007
Posts: 3525
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40

### Show Tags

15 Feb 2009, 09:24
I've already posted them: C, B, E
_________________

HOT! GMAT TOOLKIT 2 (iOS) / GMAT TOOLKIT (Android) - The OFFICIAL GMAT CLUB PREP APP, a must-have app especially if you aim at 700+ | PrepGame

Manager
Joined: 04 Jan 2009
Posts: 236

### Show Tags

15 Feb 2009, 09:50
matematikconsultant wrote:
Walker!
Sorry, not sum. Product. If f is largest, then m/f <1, n/f<1, etc and m/f +n/f + p/f +K/f +1 = mnpk ----->
mnpk<5.
As for problems, I am a trainer on GMAT and I have thought up them

ok. Then, let me ask you the question regarding the 3rd problem.
What is the sum could be thought to understand how we can express the sum and not trying to find the actual integers.
_________________

-----------------------
tusharvk

Intern
Joined: 13 Feb 2009
Posts: 21

### Show Tags

15 Feb 2009, 09:54
Walker!
Unfortunately C,C,E
Intern
Joined: 13 Feb 2009
Posts: 21

### Show Tags

15 Feb 2009, 10:08
Very simply,If f is largest, then m/f <1, n/f<1, etc and m/f +n/f + p/f +K/f +1 = mnpk ----->
mnpk<5 or in other words, mnpk = 1,or 2,or 3,or 4 ------>It is only 1,1,2,2 and 2 or 1,1,1,2 and 5
CEO
Joined: 17 Nov 2007
Posts: 3525
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40

### Show Tags

15 Feb 2009, 10:11
What is my flaw in second problem?
_________________

HOT! GMAT TOOLKIT 2 (iOS) / GMAT TOOLKIT (Android) - The OFFICIAL GMAT CLUB PREP APP, a must-have app especially if you aim at 700+ | PrepGame

Intern
Joined: 13 Feb 2009
Posts: 21

### Show Tags

15 Feb 2009, 10:32
It is the second impotant condition.
2t/3=L/3y +L/2z
L/t=2x -------> 1/3x = 1/3y +1/2z, if y<x then the decision is absent
CEO
Joined: 17 Nov 2007
Posts: 3525
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40

### Show Tags

15 Feb 2009, 10:55
matematikconsultant wrote:
It is the second impotant condition.
2t/3=L/3y +L/2z
L/t=2x -------> 1/3x = 1/3y +1/2z, if y<x then the decision is absent

The decision cannot be absent because "A car traveled from town A to town B...". In other words, a car did travel, so solution exists. We cannot forget real contest behind formulas.
_________________

HOT! GMAT TOOLKIT 2 (iOS) / GMAT TOOLKIT (Android) - The OFFICIAL GMAT CLUB PREP APP, a must-have app especially if you aim at 700+ | PrepGame

Current Student
Joined: 28 Dec 2004
Posts: 3317
Location: New York City
Schools: Wharton'11 HBS'12

### Show Tags

15 Feb 2009, 19:59
how can 2) be B or C???

lets say that example1) distance from A to B=45

speed x=12mph, speed y=15mph and speed z=18mph

then the avg speed is 15mph

however if

distance=207 miles

speed x=12mph, speed y=15mph and speed z=180 mph then avg speed is 69mph..

so knowing x or y is insuff..
CEO
Joined: 17 Nov 2007
Posts: 3525
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40

### Show Tags

16 Feb 2009, 00:22
Hi, FN!

x,y,z must satisfy conditions given in the problem.

For first example, time of first part of the trip is t/3, or 1/3*45/15=1 hour.
But, length of first part 12*1=12 miles is not equal 1/6*45~7.5 miles.

the same for your second condition.
_________________

HOT! GMAT TOOLKIT 2 (iOS) / GMAT TOOLKIT (Android) - The OFFICIAL GMAT CLUB PREP APP, a must-have app especially if you aim at 700+ | PrepGame

Current Student
Joined: 28 Dec 2004
Posts: 3317
Location: New York City
Schools: Wharton'11 HBS'12

### Show Tags

16 Feb 2009, 10:54
hi walker OK i see your logic but lets say the total distance is 3 miles

speed x=1 mph..speed y=1 mph..and speed z=100 mph..

so the avg speed is still dependednt on the speed of z?
CEO
Joined: 17 Nov 2007
Posts: 3525
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40

### Show Tags

16 Feb 2009, 11:38
z cannot be arbitrary because of initial information. z influences on time, and time influences on x. In other words, your example again doesn't fit the information. If you want to give an example, check it for fit the initial conditions and I'm pretty sure you will get av=2x.
_________________

HOT! GMAT TOOLKIT 2 (iOS) / GMAT TOOLKIT (Android) - The OFFICIAL GMAT CLUB PREP APP, a must-have app especially if you aim at 700+ | PrepGame

Re: 3 hard problems   [#permalink] 16 Feb 2009, 11:38

Go to page   Previous    1   2   [ 35 posts ]

Display posts from previous: Sort by

# 3 hard problems

Moderator: chetan2u

 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®.