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

It is currently 24 Jul 2014, 05:07

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

GMAT PREP Test 1 - Question 1

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Intern
Intern
avatar
Joined: 15 Oct 2009
Posts: 16
Followers: 0

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

GMAT PREP Test 1 - Question 1 [#permalink] New post 02 Nov 2009, 08:25
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
So not a good start to my gmat journey. I have just finished reviewing exponents from mgmat and am still not sure how this answer is derived.

If 5^ 21 + 4^ 11 = 2 * 10^ n . What is N ?

The answer is n = 21 but i do not see this. Can someone help explain?

Thanks
Manhattan GMAT Discount CodesKaplan GMAT Prep Discount CodesVeritas Prep GMAT Discount Codes
Senior Manager
Senior Manager
avatar
Joined: 18 Aug 2009
Posts: 333
Followers: 7

Kudos [?]: 155 [0], given: 13

GMAT Tests User
Re: GMAT PREP Test 1 - Question 1 [#permalink] New post 02 Nov 2009, 08:40
Please check if the question is correct.
Do you mean 5^21*4^11 = 2*10^n . What is N

If yes, then here is the explanation:
5^21*4^11 = 5^10*(5^11*4^11) = (5^10*2^11)*(10^11) = 2*10^21

Questions? Let me know.
Intern
Intern
avatar
Joined: 15 Oct 2009
Posts: 16
Followers: 0

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

Re: GMAT PREP Test 1 - Question 1 [#permalink] New post 02 Nov 2009, 09:02
Quote:
Please check if the question is correct.
Do you mean 5^21*4^11 = 2*10^n . What is N

If yes, then here is the explanation:
5^21*4^11 = 5^10*(5^11*4^11) = (5^10*2^11)*(10^11) = 2*10^21


Yes i believe that should be 5^21*4^11.

So i understand the factoring of 5^10 but, i dont see how this comes to be
Quote:
(5^10*2^11)*(10^11) = 2*10^21
. What happened to the 4^11 and how is this piece incorporated
Quote:
=2*10^n
to solve for N?
1 KUDOS received
Senior Manager
Senior Manager
avatar
Joined: 18 Aug 2009
Posts: 333
Followers: 7

Kudos [?]: 155 [1] , given: 13

GMAT Tests User
Re: GMAT PREP Test 1 - Question 1 [#permalink] New post 02 Nov 2009, 09:15
1
This post received
KUDOS
sac8513 wrote:
So i understand the factoring of 5^10 but, i dont see how this comes to be
Quote:
(5^10*2^11)*(10^11) = 2*10^21
. What happened to the 4^11 and how is this piece incorporated
Quote:
=2*10^n
to solve for N?


Ok, lets go stpe by step:

5^21*4^11 = 5^10*(5^11*4^11); Here we split 5^21 into 5^10*5^11.
5^10*(5^11*2^11*2^11); Here we split 4^11 as 2^11*2^11.
(5^10*2^11)*(5^11*2^11); Hope this step is clear
(5^10*2^10*2)*(10^11); Split 2^11 into 2*2^10 and 5^11*2^11 = (5*2)^11 = 10^11
(10^10*2)*(10^11); Here 5^10*2^10 = (5*2)^10 = 10^10
2*(10^21); Here 10^10*10^11 = 10^21

Now we know that 5^ 21 + 4^ 11 = 2 * 10^ n.
That means 2*10^21 = 2 * 10^ n
So n = 21.

Hope this is clear now. Questions? Shoot....
Intern
Intern
avatar
Joined: 15 Oct 2009
Posts: 16
Followers: 0

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

Re: GMAT PREP Test 1 - Question 1 [#permalink] New post 02 Nov 2009, 09:34
Ahhh very interesting. I definitely see it now. So these higher exponent problems need to be factored down as much as possible to create those commonalities...

Thank you very much

As mentioned this was the first problem that appeared in my practice test. What level problem would you say this is? Could these exponent questions be more difficult?
1 KUDOS received
Senior Manager
Senior Manager
avatar
Joined: 18 Aug 2009
Posts: 333
Followers: 7

Kudos [?]: 155 [1] , given: 13

GMAT Tests User
Re: GMAT PREP Test 1 - Question 1 [#permalink] New post 02 Nov 2009, 10:01
1
This post received
KUDOS
sac8513 wrote:
Ahhh very interesting. I definitely see it now. So these higher exponent problems need to be factored down as much as possible to create those commonalities...

Thank you very much

As mentioned this was the first problem that appeared in my practice test. What level problem would you say this is? Could these exponent questions be more difficult?


I would rate this as 500-600 difficulty level. At times such problems can become pain in the xxx, but can be solved using correct approach. Nothing is difficult if the correct approach is employed :)

Well, consider KUDOS if you liked my explanation ;)
Re: GMAT PREP Test 1 - Question 1   [#permalink] 02 Nov 2009, 10:01
    Similar topics Author Replies Last post
Similar
Topics:
GMAT Prep Test 1: taken 3 times - always new questions! thagem01 1 07 Aug 2012, 14:43
1 Question from PrepTest 1 laurenth 3 18 Sep 2011, 08:08
geometry question Gmat prep test 1 hb05sv 2 09 Apr 2010, 14:17
GmatPrepTest2-Question1 xlick 3 22 Feb 2009, 14:50
Gmat prep test 1 fawreel902 3 29 Dec 2007, 14:53
Display posts from previous: Sort by

GMAT PREP Test 1 - Question 1

  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®.