章节大纲

  • Coffee House Spending
    ::咖啡厅开支

    Your math teacher has a serious coffee habit. Every morning she goes to her favorite coffee house and buys a latte for $3.75. Here is a table to represent how much money she spends in a week:
    ::你的数学老师有一个严重的咖啡习惯。每天早上她去她最喜欢的咖啡屋, 买杯拿铁3.75美元。这里是一张表,用来代表她一周花多少钱:

    Money $3.75 $7.50      
    Days 1 2 3 4 5
    • Determine the total for days 3, 4 and 5 and create a ratio of money to days. 
      ::确定第3、4和5天的总数,并设定货币与日之比。
    • Use the sliders to adjust the numerator to be the money amounts and the denominator to represent the days. 
      ::使用滑动符将分子调整为货币金额和代表天数的分母。

     

    INTERACTIVE
    Coffee House Spending
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    • Use the sliders to adjust the numerator which represents money amounts and the denominator which represents days.
      ::使用滑动符调整代表金额的分子和代表天数的分母。
    • Numbers shown are rounded to the hundredths place.
      ::显示的数字四舍五入到千位。
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    1.

    Determine how much money your math teacher spent on lattes on day 3 of the week.
    ::确定你的数学老师 每周第3天在拿铁上花多少钱

    a

    $3.75

    b

    $7.50

    c

    $11.25

    d

    $15.00

     

    The table in this interactive is an example of a proportional relationship . All the ratios you set up were equal. These are also known as equivalent ratios . If your break this down into  its key components, you will see that :
    ::此交互式表格中的表格是比例关系的一个示例。 您设置的所有比率都是相等的。 这些比率也被称为等值比率。 如果您将其细分为关键组成部分, 您将会看到 :

    • A proportion is an equation that sets equivalent ratios equal to each other. All of these rates create a proportion because they are in a proportional relationship.
      ::比例是一个等式,它规定等同比率对等,所有这些比率都形成一个比例,因为它们是比例关系。
    • $3.75 is the rate of change . It describes how fast the output (the total cost) increases each day.
      ::3.75美元是变化率,说明产出(总成本)每天增长的速度。
    • The rate of change is always constant (or same) for any proportional relationship.
      ::任何比例关系的变化率总是不变(或相同)。

     


    Painting the House
    ::画房子

    Max is painting his house. He needs to cover 3,200 square feet of wall space. Based on the table below, how many gallons of paint does Max need to buy?
    ::他需要覆盖3200平方英尺的墙壁空间。根据下面的表格, Max需要买多少加仑的油漆?

    gallons 1 2 3 4 5
    square feet 400 800 1,200 1,600 2,000

    Use the sliders to change the proportions and determine how many gallons of paint are needed.
    ::使用滑块来改变比例,并确定需要多少加仑油漆。

     

    INTERACTIVE
    Painting the House
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    • Use the sliders to change the proportions and determine how many gallons of paint Max needs to buy.
      ::使用滑块来改变比例 并确定需要买多少加仑的油漆 Max.
    • Numbers shown are rounded to the hundredths place.
      ::显示的数字四舍五入到千位。
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    The rate of change of a proportional relationship is also called the constant of proportionality because for every rate , the proportion of  dependent value independent value  is constant. This constant of proportionality is commonly labeled k .   T he independent value, usually labeled x, is often in the first column of a table. The dependent value, which is usually labeled y, is commonly the second column of a table. Therefore , you can say:
    ::比例关系的变化率也称为相称性不变值,因为对于每一比率,依赖性价值的比重是不变的。这一相称性不变值通常被贴上标签 k。独立值通常被贴上标签 x,通常在表格第一列中。依赖性值通常被贴上标签 y,通常是表格第二列。因此,你可以说:

    dependent value independent value = y x = k

    ::独立值=yx=k

     


    Is it Proportional?
    ::是相称的吗?

    Determine if the following tables represent proportional relationships. If so, find the constant of proportionality and the equation. 
    ::确定下列表格是否代表比例关系。如果是,请找到相称性和等式的常数。

     

    INTERACTIVE
    Is It Proportional?
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    • Click on the all the tables that have proportional  x  and  y  values.
      ::单击所有有比例 x 和 y 值的表格。
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       Summary
    ::摘要

    • Tables can be used to determine whether or not data is proportional.
      ::可用表格确定数据是否成比例。
    • Proportional relationships have a constant rate of change or constant of proportionality, called  k .
      ::比例关系有不变的变化率或相称性不变,称为k。
    • You can use  k  to find other values within the proportional relationship.
      ::您可以使用 k 在比例关系中找到其它值 。