GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 20 Aug 2019, 15:47

### 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

# 98^(1/2) + 72^(1/2) =

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 57155

### Show Tags

13 May 2017, 14:29
2
7
00:00

Difficulty:

25% (medium)

Question Stats:

76% (01:29) correct 24% (01:44) wrong based on 513 sessions

### HideShow timer Statistics

$$\sqrt{98}+ \sqrt{72} =$$

A. $$\sqrt{170}$$

B. $$\sqrt{232}$$

C. $$\sqrt{286}$$

D. $$\sqrt{338}$$

E. $$\sqrt{420}$$

_________________
Manager
Joined: 13 May 2017
Posts: 114
Location: Finland
Concentration: Accounting, Entrepreneurship
GMAT 1: 530 Q42 V22
GMAT 2: 570 Q36 V31
GPA: 3.14
WE: Account Management (Entertainment and Sports)
Re: 98^(1/2) + 72^(1/2) =  [#permalink]

### Show Tags

13 May 2017, 14:53
5

Sent from my SM-G920F using GMAT Club Forum mobile app
##### General Discussion
Retired Moderator
Status: Long way to go!
Joined: 10 Oct 2016
Posts: 1339
Location: Viet Nam
Re: 98^(1/2) + 72^(1/2) =  [#permalink]

### Show Tags

13 May 2017, 20:06
2
Bunuel wrote:
$$\sqrt{98}+ \sqrt{72} =$$

A. $$\sqrt{170}$$

B. $$\sqrt{232}$$

C. $$\sqrt{286}$$

D. $$\sqrt{338}$$

E. $$\sqrt{420}$$

First make the prime factorization:

$$98 = 2 \times 49 = 2 \times 7^2$$
$$72=2 \times 36 =2 \times 6^2$$

$$\implies \sqrt{98}+\sqrt{72}=\sqrt{2 \times 7^2} + \sqrt{2 \times 6^2 } = 7\sqrt{2} + 6 \sqrt{2}=13\sqrt{2}=\sqrt{13^2 \times 2} = \sqrt{169 \times 2}=\sqrt{338}$$

_________________
Manager
Status: Gmat lover
Joined: 27 Mar 2017
Posts: 84
Location: India
Schools: IIMA , IIMA PGPX"18
GMAT 1: 710 Q49 V39
GPA: 3.91
Re: 98^(1/2) + 72^(1/2) =  [#permalink]

### Show Tags

15 May 2017, 09:24
98−−√+72−−√=98+72=

A. 170−−−√170

B. 232−−−√232

C. 286−−−√286

D. 338−−−√338

E. 420−−−√420
_________________
_________________
Rules for posting in verbal Gmat forum, read it before posting anything in verbal forum
Giving me + 1 kudos if my post is valuable with you

The more you like my post, the more you share to other's need.

“The great secret of true success, of true happiness, is this: the man or woman who asks for no return, the perfectly unselfish person, is the most successful.”
-Swami Vivekananda
Manager
Joined: 03 Feb 2017
Posts: 74
Location: Australia
GMAT 1: 720 Q48 V40
Re: 98^(1/2) + 72^(1/2) =  [#permalink]

### Show Tags

12 Jun 2017, 22:20
Prime factorization of 98 gives 2*(7^2)
Prime factorization of 72 gives (2^3)*(3^2)

From here we can take $$\sqrt{2}$$ as a common factor and get D as the answer
CEO
Status: GMATINSIGHT Tutor
Joined: 08 Jul 2010
Posts: 2967
Location: India
GMAT: INSIGHT
Schools: Darden '21
WE: Education (Education)

### Show Tags

13 Jun 2017, 04:49
1
Bunuel wrote:
$$\sqrt{98}+ \sqrt{72} =$$

A. $$\sqrt{170}$$

B. $$\sqrt{232}$$

C. $$\sqrt{286}$$

D. $$\sqrt{338}$$

E. $$\sqrt{420}$$

EASY WAY OUT FOR SUCH QUESTIONS IS APPROXIMATION

$$\sqrt{98}+ \sqrt{72} =9.9+8.6 =$$ 18.5

A. $$\sqrt{170} = 13.1 approx.$$

B. $$\sqrt{232}= 15.2 approx.$$

C. $$\sqrt{286}= 16.5 approx.$$

D. $$\sqrt{338}= 18.2 approx.$$ CORRECT ANSWER

E. $$\sqrt{420}= 20.5 approx.$$
_________________
Prosper!!!
GMATinsight
Bhoopendra Singh and Dr.Sushma Jha
e-mail: info@GMATinsight.com I Call us : +91-9999687183 / 9891333772
Online One-on-One Skype based classes and Classroom Coaching in South and West Delhi
http://www.GMATinsight.com/testimonials.html

ACCESS FREE GMAT TESTS HERE:22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION
Director
Joined: 12 Nov 2016
Posts: 708
Location: United States
Schools: Yale '18
GMAT 1: 650 Q43 V37
GRE 1: Q157 V158
GPA: 2.66
Re: 98^(1/2) + 72^(1/2) =  [#permalink]

### Show Tags

19 Jun 2017, 22:16
Bunuel wrote:
$$\sqrt{98}+ \sqrt{72} =$$

A. $$\sqrt{170}$$

B. $$\sqrt{232}$$

C. $$\sqrt{286}$$

D. $$\sqrt{338}$$

E. $$\sqrt{420}$$

\sqrt{98} reduces to

49 x 2=
7\sqrt{2} +...

\sqrt{72}
Reduces to 36 x 2
6\sqrt{2}

7\sqrt{2} + 6\sqrt{2} = 13 \sqrt{2}

169 x 2= 338
Board of Directors
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 4573
Location: India
GPA: 3.5
Re: 98^(1/2) + 72^(1/2) =  [#permalink]

### Show Tags

19 Jun 2017, 22:40
Bunuel wrote:
$$\sqrt{98}+ \sqrt{72} =$$

A. $$\sqrt{170}$$

B. $$\sqrt{232}$$

C. $$\sqrt{286}$$

D. $$\sqrt{338}$$

E. $$\sqrt{420}$$

$$\sqrt{98}+ \sqrt{72}$$

Or, $$7\sqrt{2}+ 6\sqrt{2}$$

Or, $$13\sqrt{2}$$

$$\sqrt{338}$$ (When we take 13 inside the square root ), hence answer will 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 )
Director
Joined: 13 Mar 2017
Posts: 731
Location: India
Concentration: General Management, Entrepreneurship
GPA: 3.8
WE: Engineering (Energy and Utilities)
Re: 98^(1/2) + 72^(1/2) =  [#permalink]

### Show Tags

19 Jun 2017, 23:59
Bunuel wrote:
$$\sqrt{98}+ \sqrt{72} =$$

A. $$\sqrt{170}$$

B. $$\sqrt{232}$$

C. $$\sqrt{286}$$

D. $$\sqrt{338}$$

E. $$\sqrt{420}$$

$$\sqrt{98}+ \sqrt{72}$$
$$= 7\sqrt{2}+ 6\sqrt{2}$$
$$= 13\sqrt{2}$$

$$= \sqrt{338}$$

_________________
CAT 2017 (98.95) & 2018 (98.91) : 99th percentiler
UPSC Aspirants : Get my app UPSC Important News Reader from Play store.

MBA Social Network : WebMaggu

Appreciate by Clicking +1 Kudos ( Lets be more generous friends.)

What I believe is : "Nothing is Impossible, Even Impossible says I'm Possible" : "Stay Hungry, Stay Foolish".
Target Test Prep Representative
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2820
Re: 98^(1/2) + 72^(1/2) =  [#permalink]

### Show Tags

20 Jun 2017, 19:12
Bunuel wrote:
$$\sqrt{98}+ \sqrt{72} =$$

A. $$\sqrt{170}$$

B. $$\sqrt{232}$$

C. $$\sqrt{286}$$

D. $$\sqrt{338}$$

E. $$\sqrt{420}$$

Let’s simplify the given expression:

√98 + √72 = √49 x √2 + √36 x √2 = 7√2 + 6√2 = 13√2

Since 13 = √169, 13√2 = √169 x √2 = √338.

_________________

# Jeffrey Miller

Jeff@TargetTestPrep.com
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

VP
Status: Learning
Joined: 20 Dec 2015
Posts: 1023
Location: India
Concentration: Operations, Marketing
GMAT 1: 670 Q48 V36
GRE 1: Q157 V157
GPA: 3.4
WE: Engineering (Manufacturing)
Re: 98^(1/2) + 72^(1/2) =  [#permalink]

### Show Tags

20 Jun 2017, 23:32
D
√98+√72=7√2+6√2=13√2=√169*2=√338
_________________
Manager
Joined: 08 Oct 2016
Posts: 201
Location: United States
Concentration: General Management, Finance
GPA: 2.9
WE: Engineering (Telecommunications)
Re: 98^(1/2) + 72^(1/2) =  [#permalink]

### Show Tags

19 Jul 2017, 02:43
For these questions I recommend two things
1. Learn Squares upto 30
2. Learn root equivalent
Now Solve
√98+√72
7√2+6√2
√2(7+6)
13√2 by approximation(√2=1.41)
13*1.4=18.2
18=324
19=361
So option D is correct choice
_________________
Got Q42,V17
Target#01 Q45,V20--April End
Senior Manager
Status: love the club...
Joined: 24 Mar 2015
Posts: 274

### Show Tags

01 Oct 2017, 16:10
Bunuel wrote:
$$\sqrt{98}+ \sqrt{72} =$$

A. $$\sqrt{170}$$

B. $$\sqrt{232}$$

C. $$\sqrt{286}$$

D. $$\sqrt{338}$$

E. $$\sqrt{420}$$

easy way

( √98+ √72 ) ^2

=96 + 72 + 2*√(2*49*36*2)

= √338

hope this helps
Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 7399
Location: United States (CA)
Re: 98^(1/2) + 72^(1/2) =  [#permalink]

### Show Tags

04 Oct 2017, 16:45
Bunuel wrote:
$$\sqrt{98}+ \sqrt{72} =$$

A. $$\sqrt{170}$$

B. $$\sqrt{232}$$

C. $$\sqrt{286}$$

D. $$\sqrt{338}$$

E. $$\sqrt{420}$$

√98 + √72 = √49 x √2 + √36 x √2 = 7√2 + 6√2 = 13√2 = √169 x √2 = √338

_________________

# Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

CEO
Joined: 12 Sep 2015
Posts: 3912
Re: 98^(1/2) + 72^(1/2) =  [#permalink]

### Show Tags

15 Oct 2017, 12:47
1
Top Contributor
Bunuel wrote:
$$\sqrt{98}+ \sqrt{72} =$$

A. $$\sqrt{170}$$

B. $$\sqrt{232}$$

C. $$\sqrt{286}$$

D. $$\sqrt{338}$$

E. $$\sqrt{420}$$

We can also solve this question with some approximation
Here are a few "nice" roots"
√49 = 7
√64 = 8
√81 = 9
√100 = 10

Since √98 is BETWEEN √81 and √100, we know that √98 is BETWEEN 9 and 10
Also, since √98 is VERY CLOSE to √100, we can conclude that √98 is much closer to 10 than it is to 9
So, we might say that √98 ≈ 9.8 or 9.9

Likewise, since √72 is BETWEEN √64 and √81, we know that √72 is BETWEEN 8 and 9
Here, √72 is pretty much halfway between √64 and √81, we might say that √72 ≈ 8.5

NOTE: As we'll soon see, we don't need to be super accurate with our approximations.
We have: √98 + √72 ≈ 9.9 + 8.5 = ≈18.4

Now let's examine a few more "nice" roots"
17² = 289. So, √289 = 17
18² = 324. So, √324 = 18
19² = 361. So, √361 = 19
Since 18.4 is BETWEEN 18 and 19, we're looking for an answer choice that is BETWEEN √324 and √361
Since √338 is the ONLY answer choice BETWEEN √324 and √361, the correct answer must be D

Cheers,
Brent
_________________
Test confidently with gmatprepnow.com
EMPOWERgmat Instructor
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 14821
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Re: 98^(1/2) + 72^(1/2) =  [#permalink]

### Show Tags

03 Dec 2017, 21:21
1
Hi All,

While this question might look a bit 'scary', the answer choices are 'spread out' enough that you can use them 'against' the prompt, do a bit of estimation and get the correct answer without too much trouble.

To start, 98 is fairly close to 100, so we can estimate the value of the first radical to be 10.
In addition, 72 is clearly more than 64, so we know that the value of the second radical is a bit more than 8.
Thus, we're looking for an answer that's fairly close to 18.

18^2= 324 and there's only one answer that's close to that....

GMAT assassins aren't born, they're made,
Rich
_________________
760+: Learn What GMAT Assassins Do to Score at the Highest Levels
Contact Rich at: Rich.C@empowergmat.com

*****Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!*****

# Rich Cohen

Co-Founder & GMAT Assassin

Special Offer: Save \$75 + GMAT Club Tests Free
Official GMAT Exam Packs + 70 Pt. Improvement Guarantee
www.empowergmat.com/
Non-Human User
Joined: 09 Sep 2013
Posts: 12053
Re: 98^(1/2) + 72^(1/2) =  [#permalink]

### Show Tags

21 Jan 2019, 08:29
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.
_________________
Re: 98^(1/2) + 72^(1/2) =   [#permalink] 21 Jan 2019, 08:29
Display posts from previous: Sort by