6.11%求“a”部分的百分比方程

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 %求“a”部分的百分比方程

  Collapse Expand

  %求“a”部分的百分比方程

  

  [Figure 1]

  播放段落

  Marcel needs a new shirt to wear to his sports banquet. When he goes to the mall, he spots a clearance rack and finds a shirt on it he likes. The original price of the shirt is $25, but the yellow ticket clearance price is smudged. If the shirt is marked down by 60%, what is the clearance price?
  ::Marcel在体育宴会上需要穿一件新衬衫。 当他去商场时,他会发现一件脱衣架,并找到一件他喜欢的衬衫。衬衫的原价是25美元,但黄票清盘价格是低的。如果脱衣衫的标记是60%,那么清盘价格是多少?

  播放段落

  In this concept, you will learn how to use the percent  equation  to find part a, the amount.
  ::在这个概念中,你将学会如何使用百分比方程式 来找到部分a, 数量。

  播放段落

  Using the Percent Equation to Find the Amount
  ::使用百分比等量来查找金额

  播放段落

  Think about the  proportion  to find the percent of a number. 
  ::想想找到数字百分比的比例 。

  $$\begin{array}{r}\frac{a}{b}=\frac{p}{100}\end{array}$$

  播放段落

  You can cross multiply  $\begin{array}{r}b\end{array}$  and  $\begin{array}{r}p\end{array}$  and  $\begin{array}{r}a\end{array}$  and 100. Then you can divide the product of  $\begin{array}{r}b\end{array}$  and  $\begin{array}{r}p\end{array}$  by 100.
  ::您可以乘以 b 和 p 乘以 b 和 a 和 a 和 100 。 然后您可以将 b 和 p 的产值除以 100 。

  播放段落

  Let’s look at a statement that uses this proportion.
  ::让我们看看使用这个比例的语句 。

  播放段落

  What is 35% of 6?
  ::6分之35%是多少?

  播放段落

  First, convert the numbers to fractions and fill in the proportion. 
  ::首先,将数字转换成分数,填充比例。

  $$\begin{array}{r}\frac{a}{6}=\frac{35}{100}\end{array}$$

  播放段落

  Next, cross multiply and solve for  $\begin{array}{r}a\end{array}$ .
  ::下一个,交叉倍数 并解决一个。

  $$\begin{array}{r}\begin{array}{rcl}100a& =& 35(6)\\ 100a& =& 210\\ a& =& 2.1\end{array}\end{array}$$

  播放段落

  Notice that by dividing by 100, you moved the decimal place two places to the left.
  ::注意,除以100后,您将小数点位移到左边两个位子。

  播放段落

  This is the same two places that the percent is represented by. This means that if you changed the percent to a decimal FIRST, you could skip a step and use an equation to find the missing value.
  ::这是百分数代表的相同两个位置。 这意味着如果将百分数修改为小数位数, 您可以跳过一步, 使用方程来查找缺失值 。

  播放段落

  Take a look at the same problem.
  ::看看同样的问题。

  播放段落

  What is 35% of 6?
  ::6分之35%是多少?

  播放段落

  First, change 35% to a decimal.
  ::首先,将35%改为小数点后一位。

  $$\begin{array}{r}35\mathrm{\%}=0.35\end{array}$$

  播放段落

  Now, multiply this decimal by 6, the base, and find  $\begin{array}{r}a\end{array}$ , the amount. Look at this equation.
  ::现在,将这个小数点乘以6, 基数, 并找到一个, 数量。 看看这个方程式 。

  $$\begin{array}{r}\begin{array}{rcl}a& =& p\mathrm{\%}(b)\\ a& =& 0.35(6)\\ a& =& 2.1\end{array}\end{array}$$

  播放段落

  Notice that you got the same answer as when you used the proportion. Converting the percent to a decimal first just simplifies the process.
  ::请注意, 您得到的答案与使用比例时相同。 将百分比转换为小数点后, 程序会简化 。

  播放段落

  Let’s try one more example. 
  ::让我们再举一个例子。

  播放段落

  What is 32% of 200?
  ::200的32%是什么?

  播放段落

  To figure this out, first change the percent to a decimal. 
  ::要弄明白这一点,首先将百分比改为小数点后一位。

  $$\begin{array}{r}32\mathrm{\%}=0.32\end{array}$$

  播放段落

  Next, multiply this decimal by 200. 
  ::下一个乘以这个十进制乘以200。

  $$\begin{array}{r}200\times 0.32=64\end{array}$$

  播放段落

  The answer is 32% of 200 is 64.
  ::答案是,200人中的32%是64人。

  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 Marcel and his shopping trip.
  ::早些时候,你被问及 马塞尔和他的购物旅行的问题。

  播放段落

  The shirt he wants to buy originally costs $25 and is marked down by 60%. But thev yellow clearance ticket is too smudged to read the new price. What is the clearance price of the shirt?
  ::他想要买的衬衫原本要花25美元,现在有60%的印记。但黄色的结关票太脏,无法读懂新的价格。 衬衫的结关价格是多少?

  播放段落

  First, if the shirt has been reduced by 60%, its clearance price is  $\begin{array}{r}100\mathrm{\%}-60\mathrm{\%}\end{array}$  or 40% of the original price. 
  ::首先,如果衬衫减少了60%,其清关价格为100%-占原价的60%或40%。

  播放段落

  First, change the percent to a decimal. 
  ::首先,将百分比改为小数点后一位。

  $$\begin{array}{r}40\mathrm{\%}=0.40\end{array}$$

  播放段落

  Next, multiply this decimal by the original price of $25. 
  ::接下来,将这个小数点乘以原价25美元。

  $$\begin{array}{r}25\times 0.40=10\end{array}$$

  播放段落

  The answer is the clearance price of the shirt is $10.
  ::答案是衬衫的清关价格是10美元

  播放段落

  Example 2
  ::例2

  播放段落

  What is 25% of 50?
  ::50的25%是多少?

  播放段落

  First, change 25% to a decimal.
  ::首先,将25%改为小数点后一位。

  $$\begin{array}{r}25\mathrm{\%}=0.25\end{array}$$

  播放段落

  Now use the equation.
  ::现在用方程式

  $$\begin{array}{r}\begin{array}{rcl}a& =& p\mathrm{\%}(b)\\ a& =& 0.25(50)\\ a& =& 12.5\end{array}\end{array}$$

  播放段落

  The answer is 25% of 50 is 12.5.
  ::答案是50分的25%是12.5分。

  播放段落

  For the following examples, use the percent equation to find each amount. Include decimals in your answer.
  ::对于以下示例, 请使用百分比方程式查找每个数量。 在您的回答中包含小数 。

  播放段落

  Example 3
  ::例3

  播放段落

  What is 20% of 16?
  ::16分的20%是多少?

  播放段落

  First, change the percent to a decimal. 
  ::首先,将百分比改为小数点后一位。

  $$\begin{array}{r}20\mathrm{\%}=0.20\end{array}$$

  播放段落

  Next, multiply this decimal by 16. 
  ::下一个乘以这个十进制乘以16。

  $$\begin{array}{r}16\times 0.20=3.2\end{array}$$

  播放段落

  The answer is 20% of 16 is 3.2.
  ::答案是,16分的20%是3.2分。

  播放段落

  Example 4
  ::例4

  播放段落

  What is 5% of 40?
  ::40分的5%是多少?

  播放段落

  First, change the percent to a decimal. 
  ::首先,将百分比改为小数点后一位。

  $$\begin{array}{r}5\mathrm{\%}=0.05\end{array}$$

  播放段落

  Next, multiply this decimal by 40.
  ::下一步,将这个小数点乘以40。

  $$\begin{array}{r}40\times 0.05=2\end{array}$$

  播放段落

  The answer is 5% of 40 is 2.
  ::答案是,40分的5%是2分。

  播放段落

  Example 5
  ::例5

  播放段落

  What is 15% of 65?
  ::65分的15%是多少?

  播放段落

  First, change the percent to a decimal. 
  ::首先,将百分比改为小数点后一位。

  $$\begin{array}{r}15\mathrm{\%}=0.15\end{array}$$

  播放段落

  Next, multiply this decimal by 65. 
  ::下一步,将这个小数点乘以65。

  $$\begin{array}{r}65\times 0.15=9.75\end{array}$$

  播放段落

  The answer is 15% of 65 is 9.75.
  ::答案是,65人中15%是9.75人。

  播放段落

  Review
  ::回顾

  播放段落

  Use the percent equation to find each amount.
  ::使用百分数方程来找到每个数量。

  播放段落
  1. What is 20% of 18?
     ::18分的20%是多少?
  播放段落
  2. What is 10% of 30?
     ::30的10%是多少?
  播放段落
  3. What is 5% of 90?
     ::90的5%是多少?
  播放段落
  4. What is 12% of 27?
     ::27的12%是12%?
  播放段落
  5. What is 18% of 30?
     ::30分的18%是多少?
  播放段落
  6. What is 50% of 88?
     ::88的50%是多少?
  播放段落
  7. What is 75% of 12?
     ::12分的75%是多少?
  播放段落
  8. What is 75% of 90?
     ::90的75%是多少?
  播放段落
  9. What is 22% of 40?
     ::40分的22%是多少?
  播放段落
  10. What is 25% of 60?
      ::60的25%是多少?
  播放段落
  11. What is 8% of 15?
      ::15分的8%是多少?
  播放段落
  12. What is 99% of 200?
      ::200的99%是多少?
  播放段落
  13. What is 90% of 12?
      ::12分之90%是多少?
  播放段落
  14. What is 18.5% of 230?
      ::230的18.5%是多少?
  播放段落
  15. What is 20.5% of 160?
      ::160的20.5%是多少?

  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