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

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Intern
Joined: 25 Aug 2005
Posts: 45
The size of a TV screen is given as the length of the [#permalink]

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14 Oct 2005, 14:07
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

The size of a TV 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
Director
Joined: 21 Aug 2005
Posts: 790

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14 Oct 2005, 14:18
E. 40

2*(side1)^2 = 21^2
2*(side2)^2 = 19^2

since side^2 = area,
(side1)^2 - (side2)^2 = 0.5 * (21-19) * (21 + 19) = 40
SVP
Joined: 28 May 2005
Posts: 1707
Location: Dhaka

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14 Oct 2005, 15:03
gsr wrote:
E. 40

2*(side1)^2 = 21^2
2*(side2)^2 = 19^2

since side^2 = area,
(side1)^2 - (side2)^2 = 0.5 * (21-19) * (21 + 19) = 40

same here. I got 40.
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Director
Joined: 14 Oct 2003
Posts: 583
Location: On Vacation at My Crawford, Texas Ranch
Re: ETS Paper Test Q9 [#permalink]

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14 Oct 2005, 15:16
AMBA wrote:
The size of a TV 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

(21/sqrt2)^2-(19/sqrt2)^2 = 80/2 = 40
Intern
Joined: 16 Oct 2005
Posts: 27
Re: ETS Paper Test Q9 [#permalink]

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16 Oct 2005, 20:38
E. 40

2*(side1)^2 = 21^2
2*(side2)^2 = 19^2

since side^2 = area,
(side1)^2 - (side2)^2 = 0.5 * (21-19) * (21 + 19) = 40

Is what you wrote.. .

Could you please explain as to how u arrived at this formula.. I did get the answer, but i guess mine was a more circuitous way?

thanks!!
GMAT Club Legend
Joined: 07 Jul 2004
Posts: 5043
Location: Singapore
Re: ETS Paper Test Q9 [#permalink]

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16 Oct 2005, 22:25
strange wrote:
E. 40

2*(side1)^2 = 21^2
2*(side2)^2 = 19^2

since side^2 = area,
(side1)^2 - (side2)^2 = 0.5 * (21-19) * (21 + 19) = 40

Is what you wrote.. .

Could you please explain as to how u arrived at this formula.. I did get the answer, but i guess mine was a more circuitous way?

thanks!!

Let the sides of the larger screen be x, then (2x^2) = 21^2-> x^2 = 21^2/2
Let the sides of the smaller screen be y, then (2y^2) = 19^2-> y^2 = 19^2/2

Difference = (21^2 - 19^2)/2 = [(21+19)(21-19)]/2 = 40(2)/2 = 40

Do you know pythagoras theroem? It's what the formulas used here are based on.
Re: ETS Paper Test Q9   [#permalink] 16 Oct 2005, 22:25
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