7.18问题解决方案，选择操作

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  问题解决方案，选择操作

  

  [Figure 1]

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  Peter is presenting a poster about beetles for science class. The average dung beetle is  $\begin{array}{r}\frac{1}{2}\end{array}$  to 1 inch long. He is also researching the Goliath beetle. This is a huge beetle at  $\begin{array}{r}4\frac{1}{2}\end{array}$  inches long. Peter wants make a comparison of the two beetles. What is the  difference  between their lengths?
  ::彼得正在为科学课张贴甲虫海报。 平均甲虫的长度是12英寸到1英寸。 他还在研究哥利亚甲虫。 这是一个4英寸到12英寸的大型甲虫。 彼得想比较这两只甲虫。 它们之间的长度有什么区别?

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  In this concept, you will use the  problem solving  strategy: choose an operation.
  ::在此概念中,您将使用解决问题的战略:选择操作。

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  Problem Solving Plan with Choosing an Operation
  ::选择操作的解决问题计划

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  When solving a problem, it is very important to read and understand the problem in  order  to figure out which operation you need to find a correct answer. This is especially important with word problems. You can identify key words in a word problem that let you know which operation to use. The four operations are addition, subtraction, multiplication and division. Here is a description of each and some key words that you can look for when reading a problem.
  ::当解决问题时,读取和理解问题非常重要,以便找出您需要找到正确答案的操作。 这对文字问题尤为重要。 您可以识别一个单词问题中的关键词, 使您知道要使用哪个操作。 四个操作是添加、 减、 乘和除。 以下描述您在阅读问题时可以查找的每个关键词和一些关键词 。

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  Addition  – a problem where two quantities are combined. Key words:  sum , total, in all, combined, and altogether
  ::添加 - 将两个数量合并的问题。 关键词:总和,合计,合计,合计,合计,合计,合计

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

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  John has 8 books and Mary has four books, how many books do they have in all?
  ::约翰有8本书 玛丽有4本书 一共有多少本书?

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  "In all" are the key words that tells you to use addition.
  ::"所有"是关键词 告诉你使用添加。

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  Subtraction  – a problem that compares two quantities. One quantity is being removed from another quantity. Key words: left, left over, take away, difference, how many more, how many less, more than, less than, compare, greater than, increased by, and decreased by
  ::减法—一个比较两个数量的问题。一个数量正在从另一个数量中去除。关键词:左、左、左、左、走、走、差、差、多、少、小、小、比、比、比、增加、减少

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

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  Karen had fifteen records, but she gave three to her friend Louise. How many does she have left?
  ::Karen有15张记录 但她给了朋友Louise3张 她还剩多少张?

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  "Left" is the key word that tells you to use subtraction.
  ::“left”是关键词, 指示您使用减法 。

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  Multiplication  – word problems using repeated addition. The key words are similar to addition, but pay attention to the addition of the same group  multiple  times. Key words: total, in all, each, every,  per , how much, at this  rate , and of
  ::乘法 - 乘法 - 使用重复添加的字词问题 。 关键词与添加相似, 但注意增加同一个组次数 。 关键词 : 总计, 每一个, 每一个, 每一个, 每个, 多少, 按这个速率计算

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

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  What is one-half of 18?
  ::18岁的一半是什么?

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  "Of" is the key word that tells you to multiply.
  ::"Of"是关键字 告诉你要乘数。

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  Division  – Division problems generally involve a situation in which a single quantity is split up into many equal-sized parts. Key words: split,  divide , shared, equal size, average, groups, and per
  ::该司的问题通常涉及一个单一数量分成许多同等大小部分的情况。

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

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  Chris has fourteen marbles. He has divided them into two groups. How many marbles are in each group?
  ::克里斯有十四颗大理石,他将这些大理石分成两组。每组有多少大理石呢?

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  In addition to the word "divide," "group" is the key word that tells you to divide.
  ::除了“divide”一词之外,“group”是指示你们分裂的关键词。

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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 Peter and the beetles.
  ::早些时候,你被问及彼得和甲虫的问题

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  Peter is comparing the difference between the size of the dung beetle, between  $\begin{array}{r}\frac{1}{2}\end{array}$  and 1 inch long, and the Goliath beetle,  $\begin{array}{r}4\frac{1}{2}\end{array}$  inches long. The key word "difference" tells Peter that he will need to subtract to find the difference.
  ::Peter正在比较粪便甲虫的大小,在12到1英寸长之间,和歌利亚甲虫的大小,在4到12英寸长之间。关键词“差异”告诉彼得,他需要减去才能找到差异。

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  $\begin{array}{r}4\frac{1}{2}-\frac{1}{2}=4\end{array}$  inches differences for a small dung beetle
  ::4 1 2 至 1 2 = 4 英寸差异,小甲虫为4 英寸差异

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  $\begin{array}{r}4\frac{1}{2}-1=3\frac{1}{2}\end{array}$  inches difference for a large dung beetle
  ::1 2 - 1 = 3 1 2 英寸差异,大粪便甲虫

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  The difference in size ranges from  $\begin{array}{r}3\frac{1}{2}\end{array}$  inches to 4 inches.
  ::面积的差别从3,12英寸到4英寸不等。

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  Example 2
  ::例2

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  Identify the key words, the operation used, and the solution to the problem.
  ::确定关键词、使用的操作和解决问题的办法。

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  Kyle has fourteen nickels. He found four more nickels in his pocket. How many nickels does he have? How much money are the nickels worth in all
  ::Kyle有14个硬币。他在他的口袋里又发现4个硬币。他有多少个硬币?这些硬币值多少钱?

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  There are two questions in this problem. The first questions is looking for the total number of nickels. The second question is looking for the value of all the nickels.
  ::这个问题有两个问题。 第一个问题是寻找镍的总数。 第二个问题是寻找所有镍的价值。

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  Start with the first question. The key words "in all" tells you to add up the nickels. 
  ::从第一个问题开始。关键词“ 全部” 指示您加起来硬币 。

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  14 nickels + 4 nickels = 18 nickels
  ::14镍+4镍=18镍

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  Then, there is a second part of the problem. A nickel is worth 5 cents. To find the value of 18 nickels, you can add 5 cents 18 times. However, notice that this involves repeated addition. Multiply the value of a nickel by 18. 
  ::问题还有另一部分。 镍值5美分。 要找到18美分的价值, 您可以增加5美分18倍。 但是, 请注意这需要重复添加。 将镍值乘以18。

  5  $\begin{array}{r}\times \end{array}$  18  $\begin{array}{r}=\end{array}$  90

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  The key word is "in all." The operations used were addition and multiplication. Kyle has 18 nickels, which is equal to 90 cents.
  ::关键词是“全部”。使用的操作是添加和乘法。凯尔有18个镍,相当于90美分。

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  Example 3
  ::例3

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  Identify the operation indicated by the key words: "in all."
  ::关键词“所有”表示的操作。

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  The key words indicate addition or multiplication.
  ::关键词表示增加或乘数。

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  Example 4
  ::例4

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  Identify the operation indicated by the key words: "left over."
  ::关键词“留下”表示的操作标识 。

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  The key words indicate subtraction.
  ::关键字表示减法。

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  Example 5
  ::例5

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  Identify the operation indicated by the key words: "split up."
  ::关键词“拆散”中显示的操作标识 。

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  The key words indicate division. 
  
  ::关键字表示区分。

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  Review
  ::回顾

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  Identify the key words, the operation used, and the solution to each problem.
  ::确定关键词、使用的操作和每个问题的解决方案。

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  1. Clara has 30 dollars. If she splits it into 5 equal groups, how many dollars will each group have?
     ::克拉拉有30美元 如果她分成5等分组
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  2. If Clara doubles this number and then splits it into 5 equal groups, how many dollars will each group have?
     ::如果克拉拉将这个数字翻倍,然后将其分成五等分组,每个组有多少美元?
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  3. What if she starts with 24 dollars? How does this change the division?
     ::如果她从24美元开始呢?
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  4. In 5 weeks, Bo made 300 dollars. What was the average amount Bo made per week?
     ::5周后 Bo赚了300美元 每周Bo的平均金额是多少?
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  5. In 10 weeks, at this rate, how much money will Bo have made in all?
     ::10周后,按这个速度, Bo能赚多少钱?
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  6. If Bo made 600 dollars in five weeks, what is the average amount made per week?
     ::如果Bo在五周内赚了600美元,每周的平均金额是多少?
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  7. Bob has 45 dollars. Clara has 23 dollars. What is the difference between the amount of money Bo and Clara have?
     ::Bob有45美元 Clara有23美元
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  8. Lakshmi reads 20 pages per hour. At this rate, how many pages will she read in 7 hours?
     ::Lakshmi每小时读20页,按这个速度,她7小时后读多少页?
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  9. Bonnie has 85 hair barrettes. Clara has 43 hair barrettes. What is the total number of hair barrettes?
     ::Bonnie有85张发夹 Clara有43张发夹 发夹总数是多少?
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  10. If Bonnie decided to give 5 of her hair barrettes away to Joanne, how many would Bonnie and Clara have left?
      ::如果Bonnie决定把5张发夹给Joanne Bonnie和Clara会离开多少人?
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  11. Each box has 12 bottles. How many bottles are in 15 boxes?
      ::每个盒子有12瓶,15盒里有多少瓶?
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  12. Five equal-sized boxes weigh 40 pounds. How much does each box weigh?
      ::5个大小相等的箱子有40磅,每个箱子的重量是多少?
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  13. Magda had 42 fish. She gave 16 of them to Peter. How many fish did Magda have left?
      ::玛格达有42条鱼,她把16条鱼给了彼得 玛格达还剩多少鱼?
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  14. Yusef has a  $\begin{array}{r}37\frac{2}{3}\end{array}$  inch long board. If he cuts it into 9 equal sized pieces, how long will each piece be?
      ::Yusef有一个3723英寸长的板子 如果他把它切成9等大小的碎片,每块还要多久?
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  15. If Yusef cuts the same board into 18 pieces, how long will each piece be?
      ::如果Yusef把同一块板切成18块 每一块还要多久?

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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