6.12百分比公式求百分比

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  百分比公式求百分比

  

  [Figure 1]

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  Shelly bought a bouquet for her teacher at the flower shop. She counted 9 red roses and 12 pink roses in the bouquet. What percent of the roses are red and what percent are pink?
  ::Shelly在花店为她的老师买了一束花。她数了9朵红玫瑰和12朵粉红色玫瑰。什么是红玫瑰和粉红色?

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  In this concept, you’ll learn how to use the percent  equation  to find  $\begin{array}{r}p\end{array}$ , the percent.
  ::在这一概念中,你会学会如何使用百分率方程来找到p,百分率。

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  Using the Percent Equation to Find the Percent
  ::使用百分率来查找百分率

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  You can use the percent equation to find the percent,  $\begin{array}{r}p\end{array}$ , of a number. When you look at this type of problem, you will be given the amount and the base, but the percent will be a mystery. Let’s think about how to solve for the percent using the percent equation.
  ::您可以使用百分率方程式来找到一个数字的百分率, p 。 当您看到这类问题时, 将会给您数量和基数, 但百分比将是一个谜。 让我们想想如何用百分率方程式解决百分率问题 。

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  Here is the percent equation once again.
  ::这是百分率方程再次出现。

  $$\begin{array}{r}a=p\times b\end{array}$$

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  Now let’s look at how to apply this equation.
  ::现在让我们来看看如何应用这个等式。

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  What percent of 70 is 14?
  ::7成的14是多少?

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  First, you have the  $\begin{array}{r}a\end{array}$  and the  $\begin{array}{r}b\end{array}$  but you are missing the percent. You can fill the given information into the  formula .
  ::首先,您拥有 a 和 b , 但是您错过了%。 您可以将给定的信息填入公式 。

  $$\begin{array}{r}\begin{array}{rcl}a& =& p\times b\\ 14& =& p(70)\end{array}\end{array}$$

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  Now you need to figure out what number times seventy is 14. Since the  operation  is  multiplication , you can do the opposite operation and divide. This is known as using the  inverse operation .
  ::现在,您需要弄清楚数字乘以 70 乘以 14 。 由于操作是乘法, 您可以进行相反的操作和除法。 这被称为使用反向操作 。

  $$\begin{array}{r}\begin{array}{rcl}\frac{14}{70}& =& p\mathrm{\%}\\ 0.2& =& p\mathrm{\%}\end{array}\end{array}$$

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  Now, change the decimal to a percent. 
  ::现在,将小数点修改为百分之一。

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  The answer 14 is 20% of 70.
  ::答案14是70的20%。

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  You must change the decimal to a percent when you are looking for a percent.
  ::当您正在寻找一个百分比时, 您必须将小数点修改为% 。

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  Examples
  ::实例

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  Example 1
  ::例1

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  Earlier, you were given a problem about Shelley and her bouquet.
  ::早些时候,你得到一个问题 关于雪莱和她的花束。

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  12 of the roses in the bouquet were pink and 9 of the roses were red. What percent of the roses were pink and what percent were red?
  ::花朵中的12朵玫瑰是粉红色的,9朵玫瑰是红色的。什么是粉红色的,什么是红色的?

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  First, find the total number of roses in the bouquet:  $\begin{array}{r}9+12=21\end{array}$ . This is the base,  $\begin{array}{r}b\end{array}$ .
  ::首先,找到花束中的玫瑰总数:9+12=21。这是基底,b。

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  Then, write the following equation.
  ::然后写下下面的方程

  $$\begin{array}{r}a=p\times b\end{array}$$

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  Next, fill in the given values, first for the pink roses and then for the red roses.
  ::接下来,填充给定的值, 先是粉红玫瑰, 然后是红玫瑰。

  $$\begin{array}{r}12=21p\mathrm{\%}\text{AND}9=21p\mathrm{\%}\end{array}$$

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  Now, divide both sides by 21.
  ::现在,将双方除以21。

  $$\begin{array}{r}\begin{array}{ccccccc}12÷21& =& 21p÷21& \text{AND}& 9÷21& =& 21p÷21\\ 0.5714& =& p& \text{AND}& 0.4286& =& p\end{array}\end{array}$$

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  Next, convert these two decimals to percents.
  ::接下来,将这两个小数点转换为百分比。

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  The answer is 57.14% of the roses in the bouquet are pink and 42.86% of them are red.
  ::答案是花朵中的玫瑰有57.14%是粉红色的,其中42.86%是红色的。

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  Example 2
  ::例2

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  What percent of 250 is 130?
  ::250分中多少是130分?

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  To figure this out, you can first write the following equation.
  ::要弄清楚这一点,您可以先写下以下方程。

  $$\begin{array}{r}a=p\times b\end{array}$$

  Next, fill in the given values.

  $$\begin{array}{r}130=250p\end{array}$$

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  Now, divide both sides by 250.
  ::现在,将双方除以250。

  $$\begin{array}{r}\begin{array}{rcl}130÷250& =& 250p÷250\\ 0.52& =& p\end{array}\end{array}$$

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  Next, convert 0.52 to a percent.
  ::接下来,将0.52转换为百分之0.5。

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  The answer is 130 is 52% of 250.
  ::答案是130是250的52%。

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  For the following examples, use the equation to find the missing percent. You may round when necessary.
  ::对于以下示例, 请使用方程式来查找缺失的百分比。 您可以在必要的时候绕行 。

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  Example 3
  ::例3

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  What percent of 50 is 15?
  ::五十分之十五是多少?

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  First, write the percent equation.
  ::首先,写百分数方程式

  $$\begin{array}{r}a=p\times b\end{array}$$

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  Next, fill in the given values.
  ::下一步,填入给定值。

  $$\begin{array}{r}15=50p\end{array}$$

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  Now, divide both sides by 50.
  ::现在,将双方除以50。

  $$\begin{array}{r}\begin{array}{rcl}15÷50& =& 50p÷50\\ 0.30& =& p\end{array}\end{array}$$

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  Next, convert 0.30 to a percent.
  ::接下来,将0.30%转换为百分之一。

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  The answer is 15 is 30% of 50.
  ::答案是15是50分的30%

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  Example 4
  ::例4

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  What percent of 80 is 25?
  ::80%是25?

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  First, write the percent equation.
  ::首先,写百分数方程式

  $$\begin{array}{r}a=p\times b\end{array}$$

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  Next, fill in the given values.
  ::下一步,填入给定值。

  $$\begin{array}{r}25=80p\end{array}$$

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  Now, divide both sides by 80.
  ::现在,将双方除以80。

  $$\begin{array}{r}\begin{array}{rcl}25÷80& =& 80p÷80\\ 0.3125& =& p\end{array}\end{array}$$

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  Next, convert 0.3125 to a percent.
  ::接下来,将0.3125转换为百分之0.3125

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  The answer is 25 is 31.25% of 80.
  ::答案是25,占80的31.25%。

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  Example 5
  ::例5

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  What percent of 100 is 12?
  ::百分之十二是多少?

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  First, write the percent equation.
  ::首先,写百分数方程式

  $$\begin{array}{r}a=p\times b\end{array}$$

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  Next, fill in the given values.
  ::下一步,填入给定值。

  $$\begin{array}{r}12=100p\end{array}$$

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  Now, divide both sides by 100.
  ::现在,将双方除以100。

  $$\begin{array}{r}\begin{array}{rcl}12÷100& =& 100p÷100\\ 0.12& =& p\end{array}\end{array}$$

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  Next, convert 0.12 to a percent.
  ::接下来,将0.12转换为百分之一。

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  The answer is 12 is 12% of 100.
  ::答案是12是100的12%。

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  Review
  ::回顾

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  Use the percent equation to find each percent. You may round your answer to the nearest whole percent if necessary.
  ::使用百分数方程式来找到每一百分数 。 您可以在必要情况下将答案折合到最近的整百分数 。

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  1. What percent of 18 is 9?
     ::十八分之九是多少?
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  2. What percent of 20 is 10?
     ::20是10是多少?
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  3. What percent of 60 is 15?
     ::60分中多少是15分?
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  4. What percent of 80 is 20?
     ::80分中多少是20分?
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  5. What percent of 25 is 10?
     ::25分中多少是10分?
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  6. What percent of 70 is 35?
     ::70是35是多少?
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  7. What percent of 36 is 18?
     ::36分中哪分是18分?
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  8. What percent of 100 is 25?
     ::百分之二十五是多少?
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  9. What percent of 10 is 5?
     ::10分之5是多少?
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  10. What percent of 98 is 90?
      ::98是90是多少?
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  11. What percent of 100 is 14?
      ::百分之十四是多少?
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  12. What percent of 200 is 90?
      ::二百分之九十是多少?
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  13. What percent of 150 is 99?
      ::一百五十分之一百五十是九十九?
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  14. What percent of 125 is 88?
      ::125比88的比例是多少?
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  15. What percent of 133 is 13?
      ::133分中13分是多少?

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  Review (Answers)
  ::回顾(答复)

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  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 。

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  Resources
  ::资源