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

It is currently 23 Oct 2014, 05:46

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

7 tricky PS and DS!!!

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Intern
Intern
avatar
Joined: 21 Jan 2007
Posts: 24
Followers: 0

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

7 tricky PS and DS!!! [#permalink] New post 18 Feb 2007, 13:44
Hi to all!!! I have problems in understanding the answers to also these questions (which i put in bold)
Could you please help me out in explaining them to me??
I managed to finish these sets, these are the last questions about them..
thanks alot!!

Riccardo

Q8:
An equilateral triangle that has an area of 9√3 is inscribed in a circle. What is the area
of the circle?
A. 6pi
B. 9pi
C. 12pi
D. 9pi √3
E. 18pi √3

Q16:
In the sequence of nonzero numbers t1, t2, t3, …, tn, …, tn+1 = tn / 2 for all positive integers
n. What is the value of t5?
(1) t3 = 1/4
(2) t1 - t5 = 15/16

Answer is C, but can’t u find it out also with each alone? (I chose D)

Q16:
If n is an integer greater than 6, which of the following must be divisible by 3?
A. n*(n+1)*(n-4)
B. n*(n+2)*(n-1)
C. n*(n+3)*(n-5)
D. n*(n+4)*(n-2)
E. n*(n+5)*(n-6)


SET 29


Q9:
A total of 100 customers purchased books at a certain bookstore last week. If these
customers purchased a total of 200 books, how many of the customers purchased only 1
book each?
(1) None of the customers purchased more than 3 books.
(2) 20 of the customers purchased only 2 books each.

Answer is C.. but actually shouldn’t it be E?

Q16:
On a certain nonstop trip, Marta averaged x miles per hour for 2 hours and y miles per
hour for the remaining 3 hours. What was her average speed, in miles per hour, for the
entire trip?
(1) 2x + 3y = 280
(2) y = x + 10

Answer is A…

SET 31

Q18:
2x + y = 12
|y| less or equal than 12

6
For how many ordered pairs (x , y) that are solutions of the system above are x
and y both
integers?
A. 7
B. 10
C. 12
D. 13 E. 14

Q26:
What is the greatest common factor of the positive integers j and k?
(1) k = j + 1
(2) jk is divisible by 5.

Answer is D, why??
Intern
Intern
User avatar
Joined: 04 Apr 2006
Posts: 35
Followers: 0

Kudos [?]: 4 [0], given: 0

Re: 7 tricky PS and DS!!! [#permalink] New post 18 Feb 2007, 14:29
eribold wrote:
Q8:
An equilateral triangle that has an area of 9√3 is inscribed in a circle. What is the area
of the circle?
A. 6pi
B. 9pi
C. 12pi
D. 9pi √3
E. 18pi √3


Area of an triangle is ah/2
Equilateral triangle has height h=√(a²-(a/2)²) = a√3/2

Area is a²√3/4
If a²√3/4=9√3
then a²/4=9, a/2=3
h=3√3

If equilateral triangle is inscribed in a circle, that circle has radius
r = 2/3*h

r = 2/3*3√3 = 2√3

Area of circle is r²pi = 2√3pi = 12pi
Intern
Intern
User avatar
Joined: 04 Apr 2006
Posts: 35
Followers: 0

Kudos [?]: 4 [0], given: 0

Re: 7 tricky PS and DS!!! [#permalink] New post 18 Feb 2007, 14:40
eribold wrote:
Q18:
2x + y = 12
|y| less or equal than 12

6
For how many ordered pairs (x , y) that are solutions of the system above are x
and y both
integers?
A. 7
B. 10
C. 12
D. 13 E. 14


Y have to be even in order to have the result when x is integer. You have 6 positive even numbers <12> -12, which gives us 13
Intern
Intern
User avatar
Joined: 04 Apr 2006
Posts: 35
Followers: 0

Kudos [?]: 4 [0], given: 0

Re: 7 tricky PS and DS!!! [#permalink] New post 18 Feb 2007, 15:23
eribold wrote:
Q16:
If n is an integer greater than 6, which of the following must be divisible by 3?
A. n*(n+1)*(n-4)
B. n*(n+2)*(n-1)
C. n*(n+3)*(n-5)
D. n*(n+4)*(n-2)
E. n*(n+5)*(n-6)


One of the multiples must be divisible by 3

Picking numbers should be fast enough, bc the pattern repeats itself after 3 numbers

A
9 10 5
10 11 6
11 12 7
12 13 8
13 14 9

B
10 12 9
11 13 10

C
9 12 4
10 13 5

D
9 13 7
10 14 8

E
9 14 3
10 15 4
11 16 5
Re: 7 tricky PS and DS!!!   [#permalink] 18 Feb 2007, 15:23
    Similar topics Author Replies Last post
Similar
Topics:
4 Tricky SC Series- #7 gmattokyo 12 31 Oct 2009, 22:03
7 other tricky ds statistics marcodonzelli 9 27 Feb 2008, 09:47
DS: positive (tricky one) financeguy 3 17 Sep 2007, 00:50
some tricky PS and DS questions nick_sun 7 26 Mar 2007, 14:02
DS - bit tricky sharadGmat 8 21 Jul 2006, 07:58
Display posts from previous: Sort by

7 tricky PS and DS!!!

  Question banks Downloads My Bookmarks Reviews Important topics  


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

Powered by phpBB © phpBB Group and phpBB SEO

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®.