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#1 2007-01-14 03:20:45

Sinthiya
Member
Registered: 2006-08-04
Posts: 2

Need help ....

hi,

Can any one help me to solve this problem?
I know the answer. But i need the steps. eek

The problem is....

There is a proportional relationship between the size of a projected image on a screen and the distance of the screen from the projector. An image that is projected onto a screen 10 feet away is a rectangle with dimensions of 2 feet by 3 feet. If the screen is moved to a distance of 15 feet from the projector, what will be the dimensions of the larger image projected onto the screen?

The choices are...

F. 3 feet by 4.5 feet
G. 4 feet by 6 feet
H. 4.5 feet by 6.75 feet
I. 7 feet by 8 feet



Bye!up

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#2 2007-01-14 05:09:38

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

Re: Need help ....

First you need to work out how much the image is scaled by.
This is done by dividing the final distance from the screen by the initial distance. In this case, that is 15/10 = 3/2.

Now you just need to multiply each dimension by this scaling factor.

2 * 3/2 = 6/2 = 3
3 * 3/2 = 9/2 = 4.5

So the first option is the correct one.


Why did the vector cross the road?
It wanted to be normal.

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#3 2007-01-14 10:32:56

Sinthiya
Member
Registered: 2006-08-04
Posts: 2

Re: Need help ....

Hi,

Thanks for your help.


mathsyperson wrote:

First you need to work out how much the image is scaled by.
This is done by dividing the final distance from the screen by the initial distance. In this case, that is 15/10 = 3/2.

Now you just need to multiply each dimension by this scaling factor.

2 * 3/2 = 6/2 = 3
3 * 3/2 = 9/2 = 4.5

So the first option is the correct one.

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