If n is a positive integer and k = 5.1 x 10^n , what is the : GMAT Data Sufficiency (DS)
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 20 Jan 2017, 03:38

### 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

# If n is a positive integer and k = 5.1 x 10^n , what is the

Author Message
TAGS:

### Hide Tags

Director
Status: No dream is too large, no dreamer is too small
Joined: 14 Jul 2010
Posts: 651
Followers: 42

Kudos [?]: 862 [1] , given: 39

If n is a positive integer and k = 5.1 x 10^n , what is the [#permalink]

### Show Tags

09 Mar 2011, 06:52
1
KUDOS
14
This post was
BOOKMARKED
00:00

Difficulty:

35% (medium)

Question Stats:

66% (02:26) correct 34% (01:28) wrong based on 781 sessions

### HideShow timer Statistics

If n is a positive integer and k = 5.1 x 10^n , what is the value of k ?

(1) 6,000 < k < 500,000
(2) k^2 = 2.601 * 10^9
[Reveal] Spoiler: OA

_________________

Collections:-
PSof OG solved by GC members: http://gmatclub.com/forum/collection-ps-with-solution-from-gmatclub-110005.html
DS of OG solved by GC members: http://gmatclub.com/forum/collection-ds-with-solution-from-gmatclub-110004.html
100 GMAT PREP Quantitative collection http://gmatclub.com/forum/gmat-prep-problem-collections-114358.html
Collections of work/rate problems with solutions http://gmatclub.com/forum/collections-of-work-rate-problem-with-solutions-118919.html
Mixture problems in a file with best solutions: http://gmatclub.com/forum/mixture-problems-with-best-and-easy-solutions-all-together-124644.html

Last edited by Bunuel on 18 Dec 2012, 07:21, edited 2 times in total.
Renamed the topic and edited the question.
Math Expert
Joined: 02 Sep 2009
Posts: 36568
Followers: 7082

Kudos [?]: 93234 [2] , given: 10553

### Show Tags

09 Mar 2011, 07:07
2
KUDOS
Expert's post
3
This post was
BOOKMARKED
Baten80 wrote:
If n is a positive integer and k = 5.1 x^n , what is the value of k ?
(1) 6,000 < k < 500,000
(2) k^2 = 2.601 * 10^9

I understand the official explanation. is there any other easy way?

If n is a positive integer and k = 5.1 * 10^n, what is the value of k ?

As n is a positive integer then k could be: 51, 510, 5,100, 51,000, ... Also note that no matter the value of n, k is always a positive number.

(1) 6,000 < k < 500,000 --> only one number from above is in this range: 51,000. Sufficient.

(2) k^2 = 2.601 * 10^9 --> we can solve quadratics to get two values of k positive and negative, but since given that k is positive then only the positive value of k will be valid. Sufficient.

_________________
Director
Status: No dream is too large, no dreamer is too small
Joined: 14 Jul 2010
Posts: 651
Followers: 42

Kudos [?]: 862 [0], given: 39

### Show Tags

09 Mar 2011, 07:31
Bunuel wrote:
Baten80 wrote:
If n is a positive integer and k = 5.1 x^n , what is the value of k ?
(1) 6,000 < k < 500,000
(2) k^2 = 2.601 * 10^9

I understand the official explanation. is there any other easy way?

If n is a positive integer and k = 5.1 * 10^n, what is the value of k ?

As n is a positive integer then k could be: 51, 510, 5,100, 51,000, ... Also note that no matter the value of n, k is always a positive number.

(1) 6,000 < k < 500,000 --> only one number from above is in this range: 51,000. Sufficient.

(2) k^2 = 2.601 * 10^9 --> we can solve quadratics to get two values of k positive and negative, but since given that k is positive then only the positive value of k will be valid. Sufficient.

I corrected the original post.
_________________

Collections:-
PSof OG solved by GC members: http://gmatclub.com/forum/collection-ps-with-solution-from-gmatclub-110005.html
DS of OG solved by GC members: http://gmatclub.com/forum/collection-ds-with-solution-from-gmatclub-110004.html
100 GMAT PREP Quantitative collection http://gmatclub.com/forum/gmat-prep-problem-collections-114358.html
Collections of work/rate problems with solutions http://gmatclub.com/forum/collections-of-work-rate-problem-with-solutions-118919.html
Mixture problems in a file with best solutions: http://gmatclub.com/forum/mixture-problems-with-best-and-easy-solutions-all-together-124644.html

GMAT Club Legend
Joined: 09 Sep 2013
Posts: 13459
Followers: 575

Kudos [?]: 163 [0], given: 0

Re: If n is a positive integer and k = 5.1 x 10^n , what is the [#permalink]

### Show Tags

21 Jun 2014, 18:59
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: 13459
Followers: 575

Kudos [?]: 163 [0], given: 0

Re: If n is a positive integer and k = 5.1 x 10^n , what is the [#permalink]

### Show Tags

21 Jul 2015, 19:38
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: 21 Oct 2014
Posts: 6
Followers: 0

Kudos [?]: 3 [0], given: 5

If n is a positive integer and k = 5.1 x 10^n , what is the valu [#permalink]

### Show Tags

23 Jul 2015, 12:47
Actually the answer D is correct.

Allow me to explain. As n is a positive integer. The values of k will be

n=1 --> 51
n+2 --> 510
n+3 --> 5,100
n+4 --> 51,000
n+5 --> 510,000

The inequality,although very wide,tells us about the only possible value of k which is 51,000. As 5100 is less than 6000 and 510,000 is more than 500,000.

Statement B is sufficient on its own. Should give a positive and negative value of K. But the question stem tells us that K is positive.

Hope this helps
Intern
Joined: 13 Dec 2015
Posts: 3
Followers: 0

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

Re: If n is a positive integer and k = 5.1 x 10^n , what is the [#permalink]

### Show Tags

16 Jul 2016, 05:34
Bunuel wrote:
Baten80 wrote:
If n is a positive integer and k = 5.1 x^n , what is the value of k ?
(1) 6,000 < k < 500,000
(2) k^2 = 2.601 * 10^9

I understand the official explanation. is there any other easy way?

If n is a positive integer and k = 5.1 * 10^n, what is the value of k ?

As n is a positive integer then k could be: 51, 510, 5,100, 51,000, ... Also note that no matter the value of n, k is always a positive number.

(1) 6,000 < k < 500,000 --> only one number from above is in this range: 51,000. Sufficient.

(2) k^2 = 2.601 * 10^9 --> we can solve quadratics to get two values of k positive and negative, but since given that k is positive then only the positive value of k will be valid. Sufficient.

could you please explain the solution of statement 2
Math Expert
Joined: 02 Sep 2009
Posts: 36568
Followers: 7082

Kudos [?]: 93234 [0], given: 10553

Re: If n is a positive integer and k = 5.1 x 10^n , what is the [#permalink]

### Show Tags

16 Jul 2016, 07:38
Maruf Iqbal wrote:
Bunuel wrote:
Baten80 wrote:
If n is a positive integer and k = 5.1 x^n , what is the value of k ?
(1) 6,000 < k < 500,000
(2) k^2 = 2.601 * 10^9

I understand the official explanation. is there any other easy way?

If n is a positive integer and k = 5.1 * 10^n, what is the value of k ?

As n is a positive integer then k could be: 51, 510, 5,100, 51,000, ... Also note that no matter the value of n, k is always a positive number.

(1) 6,000 < k < 500,000 --> only one number from above is in this range: 51,000. Sufficient.

(2) k^2 = 2.601 * 10^9 --> we can solve quadratics to get two values of k positive and negative, but since given that k is positive then only the positive value of k will be valid. Sufficient.

could you please explain the solution of statement 2

$$k^2 = 2.601 * 10^9 = 2601*10^6 = 51^2*(10^3)^2$$

$$k= \sqrt{51^2*(10^3)^2}=51*10^3=51000$$
_________________
Senior Manager
Status: Exam scheduled!!
Joined: 05 Sep 2016
Posts: 411
Location: United States (WI)
Concentration: Marketing, Technology
WE: Other (Law)
Followers: 3

Kudos [?]: 13 [0], given: 242

If n is a positive integer and k = 5.1 x 10^n , what is the [#permalink]

### Show Tags

23 Sep 2016, 08:35
D is the correct answer. Here's why:

(1) 6,000 < k < 500,000 --> n=4 because other values would put k outside of its 'bounds' that we are given with (1).

SUFFICIENT

(2) k^2 = 2.601 * 10^9 --> square root both sides to get k alone and set RHS equal to main equation and solve for n.

SUFFICIENT
If n is a positive integer and k = 5.1 x 10^n , what is the   [#permalink] 23 Sep 2016, 08:35
Similar topics Replies Last post
Similar
Topics:
7 If K is a positive integer less than 10 and N = 4,321 + K, what is the 6 09 Dec 2014, 06:38
5 If n is an integer and k = 9.87 X 10^n, what is the value of 12 22 Aug 2013, 06:05
7 If n is a positive integer and k=5.1*10^n, what is the value 7 21 Jan 2012, 08:01
6 If n is a positive integer and k=5.1*10^n, what is the value 9 21 May 2011, 09:08
3 If n is a positive integer and k = 5.1 x 10^n , what is the value of k 7 08 May 2010, 08:45
Display posts from previous: Sort by