Author 
Message 
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 45459

If a square mirror has a 30inch diagonal, what is the area of the mir [#permalink]
Show Tags
17 Feb 2016, 03:32
Question Stats:
77% (00:37) correct 23% (00:48) wrong based on 139 sessions
HideShow timer Statistics



Current Student
Joined: 21 Nov 2014
Posts: 24
Location: United States
Concentration: Marketing, Social Entrepreneurship
GPA: 3.55
WE: Brand Management (Consumer Products)

Re: If a square mirror has a 30inch diagonal, what is the area of the mir [#permalink]
Show Tags
17 Feb 2016, 04:10
1
This post received KUDOS
Bunuel wrote: If a square mirror has a 30inch diagonal, what is the area of the mirror, in inches?
A. 225 B. 450 C. 600 D. 750 E. 900
Kudos for correct solution. Let's name square sides of s, using pythagoras 30^2=s^2+s^2, this ends to s=\sqrt{450}, which is \sqrt{2*3^2*5^2}, hence square sides are 15\sqrt{2}, 15\sqrt{2}*15\sqrt{2}=450, hence, i think the correct answer is B.



Senior Manager
Joined: 20 Aug 2015
Posts: 392
Location: India

If a square mirror has a 30inch diagonal, what is the area of the mir [#permalink]
Show Tags
23 Feb 2016, 04:08
1
This post received KUDOS
Expert's post
1
This post was BOOKMARKED
Bunuel wrote: If a square mirror has a 30inch diagonal, what is the area of the mirror, in inches?
A. 225 B. 450 C. 600 D. 750 E. 900
Kudos for correct solution. Diagonal of a mirror = \(\sqrt{2}\)*side Therefore \(\sqrt{2}\)*side = 30 Side = 30/\(\sqrt{2}\) Area = 30/\(\sqrt{2}\) * 30/\(\sqrt{2}\) = 900/2 = 450 Option B



Director
Joined: 24 Nov 2015
Posts: 564
Location: United States (LA)

Re: If a square mirror has a 30inch diagonal, what is the area of the mir [#permalink]
Show Tags
09 Apr 2016, 14:35
(30/sqrt 2)^2 = 450 Correct answer  B



Director
Status: I don't stop when I'm Tired,I stop when I'm done
Joined: 11 May 2014
Posts: 554
Location: Bangladesh
Concentration: Finance, Leadership
GPA: 2.81
WE: Business Development (Real Estate)

Re: If a square mirror has a 30inch diagonal, what is the area of the mir [#permalink]
Show Tags
10 Jun 2016, 14:15
Bunuel wrote: AbdurRakib wrote: If a square mirror has a 30inch diagonal, what is the area of the mirror, in inches?
A. 225
B. 450
C. 600
D. 750
E. 900 Merging topics. Please search before posting. Thanks But, Actuality I searched on the Google but found only this link ifasquaremirrorhasa20inchdiagonalwhatisthe99359.htmlI'll search it next time on GMATCLUB to avoid mistake Thanks again
_________________
Md. Abdur Rakib
Please Press +1 Kudos,If it helps Sentence CorrectionCollection of Ron Purewal's "elliptical construction/analogies" for SC Challenges



Senior Manager
Joined: 18 Jan 2010
Posts: 254

If a square mirror has a 30inch diagonal, what is the area of the mir [#permalink]
Show Tags
14 Jun 2016, 00:18
Bunuel wrote: If a square mirror has a 30inch diagonal, what is the area of the mirror, in inches?
A. 225 B. 450 C. 600 D. 750 E. 900
Kudos for correct solution. If a square has a side a, then the length of the diagonal is \(a* \sqrt{2}\) Area of square would be \(a^2\) \(a\sqrt{2}\) = 30; squaring both sides 2\(a^2\) = 30*30 = 900 \(a^2\) = 450 > This is the area. Answer: B.



SC Moderator
Joined: 22 May 2016
Posts: 1680

If a square mirror has a 30inch diagonal, what is the area of the mir [#permalink]
Show Tags
06 Nov 2017, 12:23
Bunuel wrote: If a square mirror has a 30inch diagonal, what is the area of the mirror, in inches?
A. 225 B. 450 C. 600 D. 750 E. 900
Kudos for correct solution. Given a square's diagonal, we need side lengths to calculate area. The relationship between a square's side, s, and its diagonal, d,* is given by \(s\sqrt{2} = d\) \(s = \frac{d}{\sqrt{2}}\) The side of square (d = 30), therefore, is \(\frac{30}{\sqrt{2}}\). Leave it; no need to rationalize the denominator because it needs to be squared. Square the side length to find area: \((\frac{30}{\sqrt{2}}\) * \(\frac{30}{\sqrt{2}})\) = \(\frac{30*30}{2}\) = \(\frac{900}{2}=450\) Answer B *Although \(d = s\sqrt{2}\) probably should be in memory, it is easily derived. Two sides, \(s\), of a square, form a right isosceles triangle. Pythagorean theorem hence yields: \(s^2 + s^2 = d^2\) \(2s^2 = d^2\) \((\sqrt{2})(\sqrt{s^2})=\sqrt{d^2}\) \((\sqrt{2})s = d\), or \(s\sqrt{2}= d\)
_________________
In the depths of winter, I finally learned that within me there lay an invincible summer.  Albert Camus, "Return to Tipasa"



Target Test Prep Representative
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2442

Re: If a square mirror has a 30inch diagonal, what is the area of the mir [#permalink]
Show Tags
08 Nov 2017, 17:30
Bunuel wrote: If a square mirror has a 30inch diagonal, what is the area of the mirror, in inches?
A. 225 B. 450 C. 600 D. 750 E. 900 Since the diagonal of a square is 30: diagonal = side√2 30 = side√2 Squaring the entire equation, we have: 30^2 = side^2 x 2 900/2 = side^2 450 = side^2 = area Answer: B
_________________
Jeffery Miller
Head of GMAT Instruction
GMAT Quant SelfStudy Course
500+ lessons 3000+ practice problems 800+ HD solutions



Intern
Joined: 22 Aug 2017
Posts: 6

Re: If a square mirror has a 30inch diagonal, what is the area of the mir [#permalink]
Show Tags
09 Nov 2017, 09:09
Area = (diag 1)* (diag 2)/2
so, Area of the mirror = 30*30/2= 450 sq inch




Re: If a square mirror has a 30inch diagonal, what is the area of the mir
[#permalink]
09 Nov 2017, 09:09






