6.4%的数字

Section outline

• Select section General

  Collapse Expand

  General

  Collapse all Expand all

  • Select activity 新闻通告

    

    新闻通告 Forum
• Select section %的数字

  Collapse Expand

  %的数字

  

  [Figure 1]

  播放段落

  Taylor wants to buy a new pair of shoes. She goes to the shoe store and discovers a shelf on which all of the shoes are 60% off. She finds a pair of shoes on the shelf that are ticketed at $50. “I wonder how much money I will get back if I pay for the shoes with a $50 bill,” Taylor muses. At the checkout register, how much change will Taylor get back?
  ::泰勒想买一双新鞋。 她去了鞋店,发现了一个架子上所有鞋的60 % 。 她在架子上找到一双50美元的鞋。 “我想知道,如果我用50美元买单买鞋,我还能拿多少钱。 ”泰勒默斯(Taylor Muses ) 。 在退票登记簿上,泰勒能拿多少零钱?

  播放段落

  In this concept, you will learn to find the percent of a number using fraction multiplication.
  ::在此概念中, 您将学会使用分数乘法来找到一个数字的百分数 。

  播放段落

  Finding the Percent of a Number
  ::查找数字的百分率

  播放段落

  To work with percents you have to understand how they relate to parts and fractions.
  ::要与百分比合作, 你必须了解它们与零件和分数的关系。

  播放段落

  The table below shows the fractional equivalents for common percents.
  ::下表显示了共同百分比的分数等值。

  5%	10%	20%	25%	30%	40%	50%	60%	70%	75%	80%	90%
  $\begin{array}{r}\frac{1}{20}\end{array}$	$\begin{array}{r}\frac{1}{10}\end{array}$	$\begin{array}{r}\frac{1}{5}\end{array}$	$\begin{array}{r}\frac{1}{4}\end{array}$	$\begin{array}{r}\frac{3}{10}\end{array}$	$\begin{array}{r}\frac{2}{5}\end{array}$	$\begin{array}{r}\frac{1}{2}\end{array}$	$\begin{array}{r}\frac{3}{5}\end{array}$	$\begin{array}{r}\frac{7}{10}\end{array}$	$\begin{array}{r}\frac{3}{4}\end{array}$	$\begin{array}{r}\frac{4}{5}\end{array}$	$\begin{array}{r}\frac{9}{10}\end{array}$

  播放段落

  The word “of” in a percent problem means to multiply. If you know the fractional equivalents for common percents, you can use this information to find the percent of a number by multiplying the fraction by that number. If you want to find a part of a whole using a percent, you use multiplication to solve.
  ::百分率问题中的“ of”一词意味着乘法。如果您知道公分率的分数等同值,您可以使用此信息通过将分数乘以该数来查找数字的百分率。如果您想要使用一个百分率来找到整个中的一部分,则使用乘法来解答。

  播放段落

  Let’s look at an example.
  ::让我们举个例子。

  播放段落

  Find 40% of 45.
  ::发现40%的45分之一。

  播放段落

  First, 40% of 45 means  $\begin{array}{r}40\mathrm{\%}\times 45\end{array}$ .
  ::首先,45人中40%意味着40%×45人。

  播放段落

  Next, look at the chart. The fraction  $\begin{array}{r}\frac{2}{5}\end{array}$  is equivalent to 40%.
  ::接下来,看看图表。第2组第5部分相当于40%。

  播放段落

  Then perform the multiplication, simplifying as you go.
  ::然后进行乘法, 简化你的行进。

  $$\begin{array}{r}40\mathrm{\%}\times 45=\frac{2}{5}\times 45=\frac{2}{\underset{1}{\cancel{5}}}\times \frac{\stackrel{9}{\cancel{45}}}{1}=\frac{18}{1}=18\end{array}$$

  播放段落

  The answer is that 40% of 45 is 18.
  ::答案是,45人中40%是18人。

  播放段落

  Now, let’s look at another example using an alternate way to solve.
  ::现在,让我们看看另一个例子,用另一种方法来解决。

  播放段落

  What is 18% of 50?
  ::50分的18%是多少?

  播放段落

  First, to figure this out, you can change the percent to a fraction and then create a  proportion .
  ::首先,要弄明白这一点, 你可以将百分比改变为一个分数, 然后创建一个比例 。

  $$\begin{array}{r}\frac{18}{100}=\frac{x}{50}\end{array}$$

  播放段落

  Next, you can cross multiply and solve for  $\begin{array}{r}x\end{array}$ .
  ::下一步,您可以交叉乘数并解答 x 。

  $$\begin{array}{r}\begin{array}{rcl}100x& =& 900\\ x& =& 9\end{array}\end{array}$$

  播放段落

  The answer is 18% of 50 is 9.
  ::答案是50分的18%是9分

  播放段落

  Examples
  ::实例

  播放段落

  Example 1
  ::例1

  播放段落

  Earlier, you were given a problem about Taylor and her shoes.
  ::早些时候,你被问及泰勒和她的鞋的问题。

  播放段落

  They were ticketed at $50 but there was a 60% off sale on them. Taylor wanted to know how much money she would get back if she paid for the shoes with a $50 bill.
  ::泰勒想知道如果她用50美元的钞票买鞋,她会得到多少钱。

  播放段落

  First, 60% of 50 means  $\begin{array}{r}60\mathrm{\%}\times 50\end{array}$ .
  ::首先,50人中60%意味着60 % × 50。

  播放段落

  Next, change the percent to a fraction in  simplest form .
  ::接下来,以最简单的形式将百分比改变为分数。

  $$\begin{array}{r}60\mathrm{\%}=\frac{60}{100}=\frac{60÷20}{100÷20}=\frac{3}{5}\end{array}$$

  播放段落

  Then perform the multiplication, simplifying as you go.
  ::然后进行乘法, 简化你的行进。

  $$\begin{array}{r}60\mathrm{\%}\times 50=\frac{3}{5}\times 50=\frac{3}{\underset{1}{\cancel{5}}}\times \frac{\stackrel{10}{\cancel{50}}}{1}=\frac{30}{1}=30\end{array}$$

  播放段落

  The answer is that the shoes are marked down by $30. If Taylor pays with a $50 bill she will get $30 back.
  ::答案是,鞋子的记号是30美元,如果泰勒用50美元买单,她将得到30美元。

  播放段落

  Example 2
  ::例2

  播放段落

  Change the percent to a fraction in simplest form.
  ::以最简单的形式将百分比改变为分数 。

  播放段落

  Find 85% of 20.
  ::发现85%的20分之一。

  播放段落

  First, 85% of 20 means  $\begin{array}{r}85\mathrm{\%}\times 20\end{array}$ .
  ::首先,20人中85%意味着85%x20。

  播放段落

  Next, change the percent to a fraction in simplest form.
  ::接下来,以最简单的形式将百分比改变为分数。

  $$\begin{array}{r}85\mathrm{\%}=\frac{85}{100}=\frac{85÷5}{100÷5}=\frac{17}{20}\end{array}$$

  播放段落

  Then perform the multiplication, simplifying as you go.
  ::然后进行乘法, 简化你的行进。

  $$\begin{array}{r}85\mathrm{\%}\times 20=\frac{17}{20}\times 20=\frac{17}{\underset{1}{\cancel{20}}}\times \frac{\stackrel{1}{\cancel{20}}}{1}=\frac{17}{1}=17\end{array}$$

  播放段落

  The answer is that 85% of 20 is 17.
  ::答案是,20人中85%是17人。

  播放段落

  Example 3
  ::例3

  播放段落

  What is 10% of 50?
  ::50的10%是多少?

  播放段落

  First, 10% of 50 means  $\begin{array}{r}10\mathrm{\%}\times 50\end{array}$ .
  ::首先 50的10%意味着 10% × 50

  播放段落

  Next, look at the chart. The fraction  $\begin{array}{r}\frac{1}{10}\end{array}$  is equivalent to 10%.
  ::接下来,看看图表。第10项相当于10%。

  播放段落

  Then perform the multiplication, simplifying as you go.
  ::然后进行乘法, 简化你的行进。

  $$\begin{array}{r}10\mathrm{\%}\times 50=\frac{1}{10}\times 50=\frac{1}{\underset{1}{\cancel{10}}}\times \frac{\stackrel{1}{\cancel{50}}}{1}=\frac{5}{1}=5\end{array}$$

  播放段落

  The answer is that 10% of 50 is 5.
  ::答案是50分的10%是5分

  播放段落

  Example 4
  ::例4

  播放段落

  What is 25% of 80?
  ::80的25%是多少?

  播放段落

  First, 25% of 80 means  $\begin{array}{r}25\mathrm{\%}\times 80\end{array}$ .
  ::首先,80人中的25%意味着25%×80。

  播放段落

  Next, look at the chart. The fraction  $\begin{array}{r}\frac{1}{4}\end{array}$  is equivalent to 25%.
  ::接下来,看看图表。第14项相当于25%。

  播放段落

  Then perform the multiplication, simplifying as you go.
  ::然后进行乘法, 简化你的行进。

  $$\begin{array}{r}25\mathrm{\%}\times 80=\frac{1}{4}\times 80=\frac{1}{\underset{1}{\cancel{4}}}\times \frac{\stackrel{20}{\cancel{80}}}{1}=\frac{20}{1}=20\end{array}$$

  播放段落

  The answer is that 25% of 80 is 20.
  ::答案是80分的25%是20分。

  播放段落

  Example 5
  ::例5

  播放段落

  What is 22% of 100?
  ::百分之22%是多少?

  播放段落

  First, 22% of 100 means  $\begin{array}{r}22\mathrm{\%}\times 100\end{array}$ .
  ::首先, 22%的100 表示22% × 100 。

  播放段落

  Next, change the percent to a fraction in simplest form.
  ::接下来,以最简单的形式将百分比改变为分数。

  $$\begin{array}{r}22\mathrm{\%}=\frac{22}{100}=\frac{22÷2}{100÷2}=\frac{11}{50}\end{array}$$

  播放段落

  Then perform the multiplication, simplifying as you go.
  ::然后进行乘法, 简化你的行进。

  $$\begin{array}{r}22\mathrm{\%}\times 100=\frac{11}{50}\times 100=\frac{11}{\underset{1}{\cancel{50}}}\times \frac{\stackrel{2}{\cancel{100}}}{1}=\frac{22}{1}=22\end{array}$$

  播放段落

  The answer is that 22% of 100 is 22.
  ::答案是,百分之二十二的百分之二十二是百分之二十二。

  播放段落

  Review
  ::回顾

  播放段落

  Use fraction multiplication to find each percent of the number.
  ::使用分数乘法查找数字的每一个百分比 。

  播放段落
  1. 10% of 25
     ::占25人中的10%
  播放段落
  2. 20% of 30
     ::占30的20%
  播放段落
  3. 25% of 80
     ::80%的25%
  播放段落
  4. 30% of 90
     ::占90的30%
  播放段落
  5. 75% of 200
     ::200人中的75%
  播放段落
  6. 8% of 10
     ::占10%的8%
  播放段落
  7. 10% of 100
     ::10%(100)
  播放段落
  8. 19% of 20
     ::占20人中的19%
  播放段落
  9. 15% of 30
     ::占30的15%
  播放段落
  10. 12% of 30
      ::占30的12%
  播放段落
  11. 15% of 45
      ::45人占15%
  播放段落
  12. 25% of 85
      ::占85人中的25%
  播放段落
  13. 45% of 60
      ::60人中45%
  播放段落
  14. 50% of 200
      ::200人中的50%
  播放段落
  15. 55% of 300
      ::300人中的55%

  播放段落

  Review (Answers)
  ::回顾(答复)

  播放段落

  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 。

  播放段落

  Resources
  ::资源