BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

EXERCISES FROM GMAT PREP- NEED SOME HELP!!

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Problem Solving |
Senior | Next Rank: 100 Posts
Posts: 61
Joined: Mon Jan 18, 2010 11:09 pm
Thanked: 8 times

by Pharo » Wed Apr 04, 2012 12:13 pm
Q1:

Let's rewrite that equation.

q = 4^17 - 2^28
= (2^2)^17 - 2^28
= 2^34 - 2^28
= (2^28) * ((2^6) - 1)
= (2^28) * (64-1)
= (2^28) * (63)
= (2^28) * (7 * 3 * 3)

; hence the answer is D :)
Top
Senior | Next Rank: 100 Posts
Posts: 61
Joined: Mon Jan 18, 2010 11:09 pm
Thanked: 8 times

by Pharo » Wed Apr 04, 2012 12:34 pm
Q2:

What are you asking exactly? Or rather, what are the options? An answer to this question can be "negative" (i.e. "then the reciprocal must be negative") or "less then -10".
Top
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pm
Location: New York, NY
Thanked: 13060 times
Followed by:1906 members
GMAT Score:790

by GMATGuruNY » Wed Apr 04, 2012 2:17 pm
If n denotes a number to the left of 0 on the number line such that the square of n is less than 1/100, then the reciprocal of n must be

A. less than -10
B. between -1 and -1/10
C. between -1/10 and 0
D. between 0 and -1/10
E. greater than 10
Let n = -1/20.
This works because (-1/20)² = 1/400, and 1/400 < 1/100.
The reciprocal of n = -20.

Only answer choice A works:
-20 is less than -10.

The correct answer is A.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Top

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3835
Joined: Fri Apr 02, 2010 10:00 pm
Location: Milpitas, CA
Thanked: 1854 times
Followed by:523 members
GMAT Score:770

by Anurag@Gurome » Wed Apr 04, 2012 6:47 pm
bobdylan wrote:1) What is the greatest prime number of 4^17 - 2^28?
a) 2
b)3
c)5
d)7
e)11

Thanks!
4^17 - 2^28
= (2²)^17 - 2^28
= 2^34 - 2^28
= 2^28(2^6 - 1)
= 2^28(63)
= 2^28(7 * 3^2)

Therefore, the greatest prime factor of 4^17 - 2^28 is 7.

The correct answer is D.
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)

Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/
Top

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3835
Joined: Fri Apr 02, 2010 10:00 pm
Location: Milpitas, CA
Thanked: 1854 times
Followed by:523 members
GMAT Score:770

by Anurag@Gurome » Wed Apr 04, 2012 6:49 pm
bobdylan wrote: 2)If N denotes a number to the left of the number line such that the square of N is less than 1/100, then the reciprocal must be.....


Thanks!
n is to the left of 0 on the number line, i.e. n < 0
As n² < 1/100, n lies between -1/10 and 1/10

Hence, -1/10 < n < 0
--> 1/n < -10
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)

Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/
Top
Post new topic Post Reply
• Page 1 of 1