It is currently 20 Oct 2017, 22:26

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

Which of the following is the best approximation?

Author Message
TAGS:

Hide Tags

Intern
Joined: 09 Oct 2012
Posts: 37

Kudos [?]: 6 [0], given: 14

Which of the following is the best approximation? [#permalink]

Show Tags

11 Oct 2012, 12:56
2
This post was
BOOKMARKED
00:00

Difficulty:

15% (low)

Question Stats:

71% (00:29) correct 29% (00:25) wrong based on 276 sessions

HideShow timer Statistics

$$(\sqrt{2}+\sqrt{5})^2$$ which of the following is the best approximation?
a. 7
b. 10
c. 13
d. 15
e. 17

Is there somebody who could explain how to make this calculate quickly?
I find this question in the Gmat prep software, what is the level of the question?
[Reveal] Spoiler: OA

Kudos [?]: 6 [0], given: 14

Math Expert
Joined: 02 Sep 2009
Posts: 41892

Kudos [?]: 129054 [1], given: 12187

Re: which of the following is the best approximation? [#permalink]

Show Tags

11 Oct 2012, 13:03
1
KUDOS
Expert's post
1
This post was
BOOKMARKED
IanSolo wrote:
$$(\sqrt{2}+\sqrt{5})^2$$ which of the following is the best approximation?
a. 7
b. 10
c. 13
d. 15
e. 17

Is there somebody who could explain how to make this calculate quickly?
I find this question in the Gmat prep software, what is the level of the question?

$$(a+b)^2=a^2+2ab+b^2$$, thus $$(\sqrt{2}+\sqrt{5})^2=2+2*\sqrt{2}*\sqrt{5}+5=7+2\sqrt{10}$$.

Now, $$3^2=9$$, so $$\sqrt{10}$$ is a little bit greater than 3, which means that $$7+2\sqrt{10}\approx{7+2*3}=13$$.

P.S. I'd say it's ~600 level question.
_________________

Kudos [?]: 129054 [1], given: 12187

Senior Manager
Joined: 13 Aug 2012
Posts: 458

Kudos [?]: 541 [0], given: 11

Concentration: Marketing, Finance
GPA: 3.23
Re: Which of the following is the best approximation? [#permalink]

Show Tags

10 Dec 2012, 23:36
$$(\sqrt{2}+\sqrt{5})(\sqrt{2}+\sqrt{5})$$
$$2 + \sqrt{10 + [square_root]10} + 5[/square_root]$$
$$7 + 2\sqrt{10}$$

\sqrt{9} = 3
\sqrt{16} = 4
[fraction]10[/fraction] - a little more than 3

$$7 + 2*3 = 7 + 6 ~ 13$$

_________________

Impossible is nothing to God.

Kudos [?]: 541 [0], given: 11

GMAT Club Legend
Joined: 09 Sep 2013
Posts: 16637

Kudos [?]: 273 [0], given: 0

Re: Which of the following is the best approximation? [#permalink]

Show Tags

04 Aug 2014, 11:03
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.
_________________

Kudos [?]: 273 [0], given: 0

Manager
Joined: 11 Jun 2014
Posts: 57

Kudos [?]: 34 [0], given: 3

Concentration: Technology, Marketing
GMAT 1: 770 Q50 V45
WE: Information Technology (Consulting)
Re: Which of the following is the best approximation? [#permalink]

Show Tags

04 Aug 2014, 20:51
Its (a+b)^2 formula..

(\sqrt{2}+\sqrt{5})^2 = 2 + 5 + 2*\sqrt{2}*\sqrt{5}

7+ 2*\sqrt{10} = 7 + (~6) ~=13.

Kudos [?]: 34 [0], given: 3

GMAT Club Legend
Joined: 09 Sep 2013
Posts: 16637

Kudos [?]: 273 [0], given: 0

Re: Which of the following is the best approximation? [#permalink]

Show Tags

22 Aug 2017, 03:14
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.
_________________

Kudos [?]: 273 [0], given: 0

Re: Which of the following is the best approximation?   [#permalink] 22 Aug 2017, 03:14
Display posts from previous: Sort by