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Math Help - Ratio help

  1. #1
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    Ratio help

    Hi all

    Im currently doing some design work and need some help with ratio's

    I have worked out that 1cm in my software equals 5.5cm in the real world.

    I now need to add a border which I know is 3cm in the real world.

    So 1cm = 5.5cm

    What does 3cm equal?

    I did 5.5/3 = 0.54
    So 3 cm = 0.54 cm

    Is that right??
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  2. #2
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    Re: Ratio help

    Quote Originally Posted by RhysJG View Post
    Hi all

    Im currently doing some design work and need some help with ratio's

    I have worked out that 1cm in my software equals 5.5cm in the real world.

    I now need to add a border which I know is 3cm in the real world.

    So 1cm = 5.5cm

    What does 3cm equal?

    I did 5.5/3 = 0.54
    So 3 cm = 0.54 cm

    Is that right??
    It's hard to believe you gave this any thought at all. 1 cm corresponds to 5.5 cm. Do you really think that a larger distance in the "real" world would correspond to a smaller distance in your model?

    If the distance is three times as much in the real world, it should be three times as much in the model, not 1/3. Multiply by 3, do not divide by it.
    Thanks from Shakarri
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  3. #3
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    Re: Ratio help

    Thanks Halls but I don't think I explained it properly.

    I am using photoshop to design some window displays. I am using a photo of the front of the shop which has been set to a small size cm wise do it doesnt slow down the computer. Because of this I need to convert the size and find the ratio. So in photoshop it has a ruler and i am using that as my base.

    I discovered that objects on the photo compared to the ruler in photoshop was 1cm in photoshop = 5.5cm in the real world (in the photo)

    I had to add borders to some window frames, I know that in the real world these frames are 3 cm thick. So I need to make sure when I add them to photoshop it is to scale.

    So if 1 cm in photoshop = 5.5 cm in the real world, what is 3cm real world to photoshop?
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  4. #4
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    Re: Ratio help

    Always keep the quantity you are finding toward the right side
    Now 5.5 cm in real world = 1 cm in software
    Thus 1 cm in real world = 1/(5.5) cm in software
    and 3 cm in real world = [1/(5.5) ] * 3 cm in software
    that is 3 cm in real world will be 0.55 cm in the software
    Thanks from RhysJG
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  5. #5
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    Re: Ratio help

    Thanks makes perfect sense
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