8.20小费估算

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  小费估算

  

  [Figure 1]

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  Mary and Henry are meeting up for lunch. The total was $18.50. Since Henry helped Mary out earlier in the week, Mary offers to pay for lunch. Henry offers to pay the  tip . He’s not sure how much tip to leave, but he knows he wants to leave around 15%. How can Henry estimate 15% of $18.50?
  ::Mary和Henry在午餐时间见面。总计是18.50美元。自从Henry在一周早些时候帮助Mary吃午餐以来,Mary主动支付午餐费用。Henry主动支付小费。他不确定要离开的提示有多少,但他知道他想离开大约15 % 。 亨利怎么估计18.50美元中15%是15 % ?

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  In this concept, you will learn how to use percents to estimate tips.
  ::在这个概念中,你将学会如何使用百分比来估计小费。

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  Estimating Tips
  ::估算提示

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  A  tip  is a  sum  of money given to a person for performing a service. The  amount  of tip depends on the type of service being performed, the quality of the service, and the person giving the tip. Tips are often a  percentage  of the total cost.
  ::数额取决于所提供服务的类型、服务质量和提供数额的人。 数额通常占总费用的百分比。

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

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  John ate out for lunch. His total bill came to $12.00. He wants to leave a 15% tip.
  ::约翰在午餐时吃过东西,他的账单总额是12美元,他想留下15%的小费

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  John can take the time to calculate 15% of the total bill or he can also use what he knows about percents to estimate the approximate tip. 15% is between 10% and 20%.
  ::John可以花时间计算总帐单的15%,或者他也可以使用他所知道的百分率来估计大约小费。 15%在10%到20%之间。

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  First, calculate 10% of $12.00. 10% is also 0.1 or one-tenth. When a number is multiplied by one-tenth, move the  decimal point  one place to the left.
  ::首先,计算12.00美元的10%。10%也是0.1或1十分。当数字乘以1十分时,将小数点一移到左边。

  $$\begin{array}{r}10\mathrm{\%}\text{ of }\mathrm{\$}12.00=\mathrm{\$}\mathrm{1.20.}\end{array}$$

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  Next, use mental math again to find 20% of $12.00 by multiplying $1.20 by 2.
  ::接下来,再用心理数学 乘以1.20乘以2 来发现12美元的20%

  $$\begin{array}{r}20\mathrm{\%}\text{ of }\mathrm{\$}12.00=\mathrm{\$}\mathrm{2.40.}\end{array}$$

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  Then, estimate an amount between $1.20 and $2.40 that will be approximately 15%.
  ::然后,估计在1.20至2.40美元之间,大约为15%。

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  John can estimate that a tip between $1.75 and $2.00 is about 15% of the total bill.
  ::John可以估计,1.75美元到2.00美元之间的小费大约占总帐单的15%。

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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 Mary and Henry at lunch.
  ::之前午餐时你遇到玛丽和亨利的麻烦

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  Henry wants to leave a 15% tip on a $18.50 lunch bill. To find the amount, Henry can estimate by finding close percentages and approximating 15%.
  ::亨利想在18.50美元的午餐账单上留下15%的提示。为了找到这笔金额,亨利可以找到接近的百分比和接近15%的估计数。

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  First,  round  up the total to $20.00 to make estimating easier.
  ::首先,将总额增加到20美元,使估算工作更容易进行。

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  Next, find 10% of $20.00.
  ::接下来,找到$ $ 200.00的10%。

  $$\begin{array}{r}10\mathrm{\%}\text{ of }\mathrm{\$}20.00=\$2.00\end{array}$$

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  Then, multiply that amount by 2 to find 20% of $20.00
  ::然后,再乘以2 乘以2 发现20%的$20.00

  $$\begin{array}{r}20\mathrm{\%}\text{ of }\mathrm{\$}20.00=\$4.00\end{array}$$

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  Henry estimates that 15% of $18.50 is approximately $3.00.
  ::Henry估计,18.50美元的15%大约是3.00美元。

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  Example 2
  ::例2

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  Estimate the tip.
  ::估计小费。

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  Kelly went to lunch. Her total bill was $29.85. About how much would a 15% tip be?
  ::Kelly去吃午饭了 她的账单总额为29.85美元 15%的小费多少钱?

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  First, Kelly can round up the total to $30.00 to make estimating easier.
  ::首先,凯莉可以把总数增加到30.00美元 以便更容易估算

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  Next, use mental math to find 10% of $30.00. Move the decimal point one place to the left.
  ::接下来,使用心理数学来找到 $30.00 的10%。 将小数点点移到左边 。

  $$\begin{array}{r}10\mathrm{\%}\text{ of }\mathrm{\$}30.00=\mathrm{\$}\mathrm{3.00.}\end{array}$$

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  This time, use mental math to find half of $3.00. Half of $3.00 is also 5% of $30.00.
  ::这一次,用心理数学来找出 3美元的一半。3美元的一半也是3美元的一半。

  $$\begin{array}{r}\text{Half of }\mathrm{\$}3.00=\mathrm{\$}1.50\end{array}$$

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  Lastly, add the 5% to the 10% to find 15%.
  ::最后,在10%中加上5%,以找到15%。

  $$\begin{array}{r}\mathrm{\$}3.00+\mathrm{\$}1.50=\mathrm{\$}4.50\end{array}$$

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  Kelly estimates that a 15% tip will be $4.50.
  ::Kelly估计15%的小费是4.50美元

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  Example 3
  ::例3

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  Estimate a 15% tip on $25.00.
  ::估计25.00美元上下15%的小费

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  First, find 10% of $25.00.
  ::首先,找到25美元中的10%。

  $$\begin{array}{r}10\mathrm{\%}\text{ of }\mathrm{\$}25.00=\mathrm{\$}2.50\end{array}$$

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  Next, find half of $2.50 and add it to $2.50
  ::接下来,找到2.50美元的一半,再加到2.50美元

  $$\begin{array}{r}\mathrm{\$}2.50+\mathrm{\$}1.25=\mathrm{\$}3.75\end{array}$$

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  A 15% tip on $25.00 is $3.75.
  ::$25.00上15%的提示是$3.75.

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  Example 4
  ::例4

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  Estimate a 15% tip on $18.00.
  ::估计18.00美元有15%的小费

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  First, find 10% of $18.00
  ::首先,找到18美元中的10%

  $$\begin{array}{r}10\mathrm{\%}\text{ of }\mathrm{\$}18.00=\mathrm{\$}1.80\end{array}$$

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  Next, multiply $1.80 by 2 to find 20%
  ::下一步,乘1.8美元乘以2 以找到20%

  $$\begin{array}{r}\mathrm{\$}1.80\times 2=\mathrm{\$}3.60\end{array}$$

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  Then, estimate an amount between $1.80 and $3.60 that will be approximately 15%.
  ::然后,估计在1.8美元到3.60美元之间,大约为15%。

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  A 15% tip on $18.00 is between $2.50 and $3.00.
  ::$18.00上15%的小费 在2.50美元到3.00美元之间

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  Example 5
  ::例5

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  Estimate a 15% tip on $36.50.
  ::估计36.50美元有15%的小费

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  First, round up the total to $40.00 to make estimating easier.
  ::首先,将总额增加到40.00美元,使估算工作更容易进行。

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  Next, find 10% of $40.00.
  ::接下来,找到40.00的10%。

  $$\begin{array}{r}10\mathrm{\%}\text{ of }\mathrm{\$}40.00=\mathrm{\$}\mathrm{4.00.}\end{array}$$

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  This time, find half of $4.00. Add the 10% and 5%.
  ::这一次,找到一半的4.00美元,加上10%和5%。

  $$\begin{array}{r}\text{Half of }\mathrm{\$}4.00=\mathrm{\$}2.00\end{array}$$

  $$\begin{array}{r}\mathrm{\$}4.00+\mathrm{\$}2.00=\mathrm{\$}6.00\end{array}$$

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  Since you rounded up the bill to $40, 15% of $36.50 is a little less than $6.00.
  ::既然你把帐单归结为40美元,36.50美元的15%略低于6.00美元。

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  A 15% tip on $36.50 is between $5.25 and $6.00.
  ::36.50的15%的小费在5.25美元到6.00美元之间。

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  Review
  ::回顾

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  Estimate the following tips using 15%. Round your answer to the nearest whole cent.
  ::使用 15% 估算以下提示。 将您的答复舍入到最近的整个百分点 。

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  1. A tip on $10.00
     ::$10.00 的提示
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  2. A tip on $18.00
     ::$18.00的小费$18.00
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  3. A tip on $25.00
     ::25.00美元的小费
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  4. A tip on $30.00
     ::$$30.00的小费$30.00
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  5. A tip on $15.00
     ::$15.00的小费
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  6. A tip on $47.00
     ::有关47.00美元的小费
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  7. A tip on $89.00
     ::89.00美元的小费
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  8. A tip on $121.00
     ::121.00美元的小费
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  9. A tip on $135.00
     ::135.00美元的小费
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  10. A tip on $112.50
      ::112.50美元的小费
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  11. A tip on $127.75
      ::有关127.75美元的情报
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  12. A tip on $135.50
      ::关于135.50美元的小费
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  13. A tip on $97.78
      ::有关9778美元的情报
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  14. A tip on $88.67
      ::八八块六,八八块六,八八块六
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  15. A tip on $99.20
      ::关于99.20美元的情报

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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