章节大纲

  • Percent Equations 
    ::百分比比例

    The percent equation is often used to solve problems. It goes like this:
    ::百分比方程式通常用于解决问题。

    Rate × Total = Part or R %   of Total is Part

    ::比率x总计=占总和部分%是部分

    Rate is the ratio that the percent represents ( R % in the second version).
    ::比率是百分比所代表比率(第二版为R%)。

    Total is often called the base unit .
    ::总数通常称为基准单位。

    Part is the amount we are comparing with the base unit.
    ::部分是我们与基准单位比较的金额。

    Finding a Percent of a Total 
    ::占总数的百分比

    Find 25% of $80.
    ::找到80元的25%

    We are looking for the part . The total is $80. ‘of’ means multiply. R % is 25%, so we can use the second form of the equation: 25% of $80 is Part, or 0.25 × 80 = Part .
    ::我们正在寻找这部分。 总计80美元。 ` of ' 表示乘法。 R%为25%, 所以我们可以使用第二种方程式: 80美元的25%是 part, 或 0.25x80= Part 。

    0.25 × 80 = 20 , so the Part we are looking for is $20 .
    ::0.25x80=20, 所以我们要找的部分是20美元。

    Expression Values and Percentages 
    ::表达式数值和百分比

    Express $90 as a percentage of $160.
    ::90美元作为160美元的百分比。

    This time we are looking for the rate . We are given the part ($90) and the total ($160). Using the rate equation, we get Rate × 160 = 90 . Dividing both sides by 160 tells us that the rate is 0.5625, or 56.25%.
    ::这一次,我们正在寻找利率。我们得到了部分(90美元)和总额(160美元 ) 。 使用利率方程式,我们得到的利率为xx160=90。 双方分出160,这告诉我们,利率为0.5625,即56.25%。

    Finding the Total Sum 
    ::查找总和

    $50 is 15% of what total sum?
    ::50美元是总金额的15%?

    This time we are looking for the total . We are given the part ($50) and the rate (15%, or 0.15). Using the rate equation, we get 0.15 × Total = $ 50 . Dividing both sides by 0.15, we get Total = 50 0.15 ≈ 333.33 . So $50 is 15% of $333.33.
    ::这一次,我们正在寻找总计。我们得到了部分(50美元)和利率(15%,或0.15美元 ) 。 使用率方程式,我们得到0.15xTal=50美元。 双方以0.15分立,我们得到总计=50015+333.33。 因此,50是333.33的15%。

    Example
    ::示例示例示例示例

    Example 1
    ::例1

    $96 is 12% of what total sum?
    ::96美元占总金额的12%?

    This time we are looking for the total . We are given the part ($96) and the rate (12%, or 0.12). Using the rate equation, we get 0.12 × Total = $ 96 . Dividing both sides by 0.15, we get Total = 96 0.12 = 800 . So $96 is 12% of $800.
    ::这一次,我们正在寻找总计。 我们得到了部分( 96美元) 和利率( 12% 或 0.12 ) 。 使用利率方程式, 我们得到0. 12x 美元= 96。 双方分出0. 15, 我们得到总计= 960.12= 800。 因此, 96美元是800美元的12% 。

    Review 
    ::回顾

    Find the following.
    ::找到以下线索。

    1. 30% of 90
      ::占90的30%
    2. 27% of 19
      ::19个占27%
    3. 16.7% of 199
      ::199年占16.7%
    4. 11.5% of 10.01
      ::占10.01的11.5%
    5. 0.003% of 1,217.46
      ::1 217.46美元中的0.000%
    6. 250% of 67
      ::占67人中的250%
    7. 34.5% of y
      ::y的34.5%
    8. 17.02% of y
      ::17.02%y
    9. x% of 280
      ::占280人中的x%
    10. a% of 0.332
      ::a 占0.332的%
    11. y % of 3 x
      ::占 3x 3x 的 y%

    Review (Answers)
    ::回顾(答复)

    Click to see the answer key or go to the Table of Contents and click on the Answer Key under the 'Other Versions' option.
    ::单击可查看答题键, 或转到目录中, 单击“ 其他版本” 选项下的答题键 。

    Texas Instruments Resources
    ::得克萨斯州工具资源

    In the CK-12 Texas Instruments Algebra I FlexBook® resource, there are graphing calculator activities designed to supplement the objectives for some of the lessons in this chapter. See .
    ::在CK-12得克萨斯州仪器代数I FlexBook资源中,有图表计算活动,旨在补充本章某些经验教训的目标。