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

 It is currently 17 Jul 2018, 21:25

### 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

# The size of a television screen is given as the length of

Author Message
TAGS:

### Hide Tags

Manager
Status: GMAT Preperation
Joined: 04 Feb 2010
Posts: 98
Concentration: Social Entrepreneurship, Social Entrepreneurship
GPA: 3
WE: Consulting (Insurance)
The size of a television screen is given as the length of [#permalink]

### Show Tags

27 Sep 2010, 23:44
3
00:00

Difficulty:

25% (medium)

Question Stats:

75% (01:31) correct 25% (01:36) wrong based on 146 sessions

### HideShow timer Statistics

The size of a television screen is given as the length of the screen’s diagonal. If the screens were flat, then the area of a square 21-inch screen would be how many square inches greater than the area of a square 19-inch screen?

A. 2
B. 4
C. 16
D. 38
E. 40
Math Expert
Joined: 02 Sep 2009
Posts: 47043
Re: did not understand the logic [#permalink]

### Show Tags

27 Sep 2010, 23:49
2
1
vanidhar wrote:
the square of a television screen is given as a length of the diagoal. If the screens were flat, then the area of the 21in screen would be how many square inches greater than the area of a 19in screen ?

2
4
16
38
40

$$d_1=21$$ and $$d_2=19$$ --> $$area_{square}=\frac{d^2}{2}$$ --> $$area_1-area_2=\frac{(d_1)^2}{2}-\frac{(d_2)^2}{2}=\frac{21^2-19^2}{2}=\frac{(21-19)(21+19)}{2}=\frac{2*40}{2}=40$$

_________________
Retired Moderator
Joined: 02 Sep 2010
Posts: 775
Location: London
Re: did not understand the logic [#permalink]

### Show Tags

27 Sep 2010, 23:50
vanidhar wrote:
the square of a television screen is given as a length of the diagoal. If the screens were flat, then the area of the 21in screen would be how many square inches greater than the area of a 19in screen ?

2
4
16
38
40

Answer = Area(square with diagnol 21) - Area(square with diagnol 19)

If diagnol = x. Then side = x/root(2) & area = x^2/2

So answer = $$\frac{21^2-19^2}{2} = \frac{40*2}{2} = 40$$

_________________
Manager
Joined: 19 Aug 2010
Posts: 69
Re: The size of a television screen [#permalink]

### Show Tags

25 Dec 2010, 08:15
2
the diagonal of a square is always $$side*\sqrt{2}$$
and the side of a square is vice versa always $$\frac{diagonal}{\sqrt{2}}$$

Therefore:
area of the bigger one is $$(\frac{21}{\sqrt{2}})^2$$
area of the smaller one is $$(\frac{19}{\sqrt{2}})^2$$
and the difference is = 40
Manager
Joined: 27 Jul 2010
Posts: 172
Location: Prague
Schools: University of Economics Prague
Re: did not understand the logic [#permalink]

### Show Tags

25 Dec 2010, 17:40
This question supposes that the TV-screen has the shape of a square?

Can this be solved for the rectangle as well?
_________________

You want somethin', go get it. Period!

Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 2924
Location: United States (CA)
Re: The size of a television screen is given as the length of [#permalink]

### Show Tags

22 Sep 2017, 07:45
vanidhar wrote:
The size of a television screen is given as the length of the screen’s diagonal. If the screens were flat, then the area of a square 21-inch screen would be how many square inches greater than the area of a square 19-inch screen?

A. 2
B. 4
C. 16
D. 38
E. 40

Let’s determine the side of the square 21-inch screen (i.e., the diagonal of the screen is 21 inches). Recall that the diagonal of a square is equal to side√2.

21 = side√2

21/√2 = side

Since area is side^2, the area of the 21-inch screen is (21/√2)^2 = 441/2.

Let’s determine the side of the square 19-inch screen:

19 = side√2

19/√2 = side

The area of the 19-inch screen is (19/√2)^2 = 361/2.

Thus, the difference is 441/2 - 361/2 = 80/2 = 40.

Alternate solution:

We are given two square TV screens with diagonals 21 and 19, respectively. We have to determine the difference between the areas of the screens. Recall that the area of a square, given its diagonal d, is A = d^2/2. Thus, the area of the 21-inch screen is 21^2/2 = 441/2 and the area of the 19-inch screen is 19^2/2 = 361/2. Therefore, the difference in areas is 441/2 - 361/2 = 80/2 = 40.

_________________

Scott Woodbury-Stewart
Founder and CEO

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

Re: The size of a television screen is given as the length of   [#permalink] 22 Sep 2017, 07:45
Display posts from previous: Sort by

# Events & Promotions

 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®.