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- - **Finding the width of a uniform border**
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Finding the width of a uniform borderA mural is to be painted on a wall that is 15 units long and 12 units high. A border of uniform width is to surround the mural. If the mural is to cover 75% of the area of the wall, how wide must the border be? |

Re: Finding the width of a uniform borderThe "75%..." part is the easiest to tackle. The wall has area 12 x 15 = 180 (square units), so we want our mural to have area .75*180 = 135 (square units). Now we determine the dimensions of the mural. The requirement of a "uniform border" means that the mural will have dimensions (15 - 2x)*(12 - 2x), where x is the width of the border. ^ deducing this is often the hardest part of problems like this, so draw a picture and see why my claim is true. So (15 - 2x)*(12 - 2x) = 135 is the equation for the area of the mural. FOIL, get in standard form, then factor/quadratic formula. |

Re: Finding the width of a uniform borderLet W be the width and H be the height of the wall, and B be the width of the border. We then require: Application of the quadratic formula yields: Letting W = 15 m and H = 12 m, we find: The only root that makes sense is |

Re: Finding the width of a uniform borderZOMG you don't know? so nooby |

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