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

It is currently 09 Jul 2014, 17:51

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

root(16*20+8*32)=

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
1 KUDOS received
Intern
Intern
avatar
Joined: 23 Apr 2012
Posts: 1
Followers: 0

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

root(16*20+8*32)= [#permalink] New post 23 Apr 2012, 08:35
1
This post received
KUDOS
00:00
A
B
C
D
E

Difficulty:

  25% (low)

Question Stats:

82% (01:48) correct 17% (01:31) wrong based on 75 sessions
\sqrt{16*20+8*32}=

A. 4\sqrt{20}

B. 24

C. 25

D. 4\sqrt{20}+8\sqrt{2}

E. 32

This question really should not be difficult, but the explanation given by GMAC seems to violate the rules of operations PEMDAS. sqrt((16)(20)+(16)(16)) simplified to... sqrt((16)(20+16)) I understand eliminating one of the 16s on the right since its essentially 16 squared, but I dont understand why they can then add 20 and 16 BEFORE multiplying by the left-hand 16
[Reveal] Spoiler: OA

Last edited by Bunuel on 23 Apr 2012, 09:28, edited 1 time in total.
Edited the question
Expert Post
1 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 18474
Followers: 3184

Kudos [?]: 21139 [1] , given: 2532

Re: Square root((16)(20)+(8)(32)) = [#permalink] New post 23 Apr 2012, 09:31
1
This post received
KUDOS
Expert's post
JordanKatz wrote:
This question really should not be difficult, but the explanation given by GMAC seems to violate the rules of operations PEMDAS. sqrt((16)(20)+(16)(16)) simplified to... sqrt((16)(20+16)) I understand eliminating one of the 16s on the right since its essentially 16 squared, but I dont understand why they can then add 20 and 16 BEFORE multiplying by the left-hand 16

i attached a screen shot of OGs explanation



\sqrt{16*20+8*32}=

A. 4\sqrt{20}

B. 24

C. 25

D. 4\sqrt{20}+8\sqrt{2}

E. 32

Everything is correct there.

\sqrt{16*20+8*32}= --> factor out 16: \sqrt{16(20+8*2)}=\sqrt{16(20+16)}=\sqrt{16*36}=4*6=24.

Answer: B.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Senior Manager
Senior Manager
User avatar
Joined: 01 Apr 2010
Posts: 300
Location: Kuwait
Schools: Sloan '16 (M)
GMAT 1: 710 Q49 V37
GPA: 3.2
WE: Information Technology (Consulting)
Followers: 4

Kudos [?]: 54 [0], given: 11

GMAT Tests User
Re: root(16*20+8*32)= [#permalink] New post 23 Apr 2012, 15:45
Got B, but took 2 minutes get the number, I like the math manipulation strategy above, much quicker.
Senior Manager
Senior Manager
User avatar
Joined: 23 Oct 2010
Posts: 383
Location: Azerbaijan
Concentration: Finance
GMAT 1: 690 Q47 V38
Followers: 11

Kudos [?]: 119 [0], given: 72

GMAT ToolKit User
Re: root(16*20+8*32)= [#permalink] New post 30 Jul 2013, 04:03
sqrt(4*4*4*5+4*4*4*4)=sqrt(4*4*4*4*9)=2*2*2*3=8*3=24
_________________

Happy are those who dream dreams and are ready to pay the price to make them come true

Re: root(16*20+8*32)=   [#permalink] 30 Jul 2013, 04:03
Display posts from previous: Sort by

root(16*20+8*32)=

  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®.