It is currently 13 Dec 2017, 20:38

Decision(s) Day!:

CHAT Rooms | Ross R1 | Kellogg R1 | Darden R1 | Tepper R1


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.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

What is 157609^(1/2)?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Senior SC Moderator
User avatar
D
Joined: 14 Nov 2016
Posts: 1254

Kudos [?]: 1363 [0], given: 440

Location: Malaysia
GMAT ToolKit User Premium Member CAT Tests
What is 157609^(1/2)? [#permalink]

Show Tags

New post 13 Jan 2017, 21:34
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

68% (01:02) correct 32% (00:39) wrong based on 82 sessions

HideShow timer Statistics

What is \(\sqrt{157609}\)?

(A) 323
(B) 378
(C) 392
(D) 397
(E) 403
[Reveal] Spoiler: OA

_________________

"Be challenged at EVERY MOMENT."

“Strength doesn’t come from what you can do. It comes from overcoming the things you once thought you couldn’t.”

"Each stage of the journey is crucial to attaining new heights of knowledge."

Rules for posting in verbal forum | Please DO NOT post short answer in your post!


Last edited by hazelnut on 20 Jan 2017, 06:50, edited 2 times in total.

Kudos [?]: 1363 [0], given: 440

Manager
Manager
avatar
B
Joined: 25 Jun 2016
Posts: 61

Kudos [?]: 86 [0], given: 4

GMAT 1: 780 Q51 V46
Re: What is 157609^(1/2)? [#permalink]

Show Tags

New post 13 Jan 2017, 22:01
One way to attack this problem is to consider squaring the answer choices. When squared, the right answer will be 157609. We want to minimize calculation, so we want to look for shortcuts.

First, if the square of a number ends in 9 then the number itself will end in 3 or 7. So B and C are gone. We could have also noticed that both B and C are even, so their squares will also be even.

E, 403, is pretty close to a number that's easy to work with, 400, so let's consider E next. 400^2 = 160000, so 403^2 will be bigger still. Our number is smaller, so E is gone.

If we start multiplying A, 323, out the long way we find that the tens digit is 2, not 0. Eliminate.

D is all that's left.

Kudos [?]: 86 [0], given: 4

Board of Directors
User avatar
G
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 3111

Kudos [?]: 1146 [0], given: 327

Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)
GMAT ToolKit User Premium Member
Re: What is 157609^(1/2)? [#permalink]

Show Tags

New post 13 Jan 2017, 23:07
1
This post was
BOOKMARKED
ziyuenlau wrote:
What is \(\sqrt{157609}\)?

(A) 323
(B) 378
(C) 392
(D) 397
(E) 403


\(300^2 = 9000\)
\(400^2 = 16000\)
\(350^2 = 122500\)

So, The number must be Greater than 350 and the units digit of the number must end in 3 and 7...

Among the given options only (D) fits in perfectly , hence, correct answer must be (D)


_________________

Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only )

Kudos [?]: 1146 [0], given: 327

Intern
Intern
avatar
B
Joined: 09 Jan 2017
Posts: 6

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

Re: What is 157609^(1/2)? [#permalink]

Show Tags

New post 13 Jan 2017, 23:41
157609 is odd so its sq rt cannot be even. Eliminate B,C

Option E is 403, 400 is sq rt of 160000 which is greater than 157609. We are left with 323 and 397. Now 350 square is 122500 so 323 can be eliminated. Hence answer is d 397

Sent from my ASUS_Z010D using GMAT Club Forum mobile app

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

Intern
Intern
avatar
B
Joined: 28 Aug 2016
Posts: 15

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

Re: What is 157609^(1/2)? [#permalink]

Show Tags

New post 19 Nov 2017, 06:34
Since the units digit has to be 9 so only 323 and 397 will remain, then we can take a square of 320 and determine that 323 will not be our answer coz 320^2= 102400 so therefore D is our answer

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

BSchool Forum Moderator
User avatar
D
Joined: 26 Feb 2016
Posts: 1702

Kudos [?]: 750 [0], given: 20

Location: India
Concentration: General Management, Leadership
WE: Sales (Retail)
Premium Member CAT Tests
Re: What is 157609^(1/2)? [#permalink]

Show Tags

New post 19 Nov 2017, 08:08
hazelnut wrote:
What is \(\sqrt{157609}\)?

(A) 323
(B) 378
(C) 392
(D) 397
(E) 403


\(400^2 = 160000\)
Also, for the last digit 9, the square root could be 3 or 7 because \(\sqrt{49} = 7\) and \(\sqrt{9} = 3\)
Since the number in question is slightly below 160000, the square root cannot be 403.

Therefore, the number must be 397(Option D)

Another method to tests our answer is \((397)^2 = (400 - 3)^2 = 160000 + 9 - 2(400)(3) = 160009 - 2400 = 157609\)
_________________

Stay hungry, Stay foolish

2017-2018 MBA Deadlines

Class of 2020: Rotman Thread | Schulich Thread
Class of 2019: Sauder Thread

Kudos [?]: 750 [0], given: 20

Re: What is 157609^(1/2)?   [#permalink] 19 Nov 2017, 08:08
Display posts from previous: Sort by

What is 157609^(1/2)?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


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

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

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®.