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  • 公制单位换算的估计

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    Billy is on a trip to Canada with his family. He is trying to get used to seeing all of the distances and speed limits on road signs given in terms of kilometers instead of miles! He sees a sign that says “maximum 50 km/h”. He knows that means 50 kilometers per  hour , but he wonders if that is a fast speed or a slow speed. How can Billy estimate what 50 kilometers per hour would be in miles per hour?
    ::比利和他的家人正在前往加拿大。 他试图习惯于看到路标上以公里而不是以英里计的距离和速度限制。 他看到一个标语说“最大50公里/小时 ” 。 他知道这意味着每小时50公里,但他想知道这是快速还是慢速。 比利如何估计每小时50公里的长度?

    In this concept, you will learn how to estimate  equivalence  between metric and customary units of measure.
    ::在这个概念中,你们将学会如何估计计量单位和习惯计量单位之间的等值。

    Estimating Conversion to Metric Units
    ::转换为计量单位的估算估计数

    Recall that there are two primary systems of measurement that you can use.
    ::回顾有两种主要测量系统可供使用。

    1. The  customary system  is the system of measurement primarily used in the United States. Units in this system include the inch,  foot ,  mile , pound, and  cup .
      ::习惯系统是主要在美国使用的测量系统,该系统的单位包括英寸、英尺、里程、磅和杯子。
    2. The  metric system  is the system of measurement primarily used in science and in countries outside of the United States. Units in this system include the  meter , liter, and gram.
      ::衡量系统是主要用于科学和美国以外国家的测量系统,该系统的单位包括仪表、升数和克数。

    You will encounter both metric units and customary units. Therefore, it’s important to develop a general idea of the equivalence between the two systems.
    ::您将遇到测量单位和习惯单位。 因此,必须形成两种系统之间等同的一般概念。

    The table below shows the approximate metric equivalents for common customary units.
    ::下表显示共同习惯单位的大致计量等值。

    Approximate Metric Equivalents for Common Customary Units
    Customary Unit  Metric Unit
    1 inch 25.4 millimeters
    1 foot 30.48 
    1  yard 0.91 meter
    1 mile 1.61 kilometers
    1 teaspoon  4.93 milliliters
    1 cup 0.24 liter
    1  pint 0.47 liter
    1  quart 0.95 liter
    1  gallon 3.79 liters
    1 ounce 28.35 grams
    1 pound 0.45 kilogram

    Notice how in this table all of the customary units are given in units of 1. So, for example, since 1 foot is about 30.48 centimeters, to convert 2 feet into centimeters just multiply 30.48 by 2 to get 60.96 centimeters. If you had a measurement in centimeters and wanted to estimate the number of  inches , you could reverse the process and divide by 30.48.
    ::在本表中,所有习惯单位的单位都是 1 的单位。 因此,例如,1英尺大约为 30.48 厘米, 将2英尺转换为 厘米只乘以30.48 乘以 2 乘以 6 096 厘米。 如果您用厘米计来测量,并且想估计英寸数, 就可以将过程倒转30.48 。

    Often you will just want to get a general idea of what a given measurement would be in the other system of measurement. If this is the case, you can use the table above and your estimation skills to determine an approximate equivalence.
    ::通常,你只想大致了解另一种计量系统中的某一计量将是什么。如果是这样,你可以使用上表和估算技能来确定大致等值。

    Here is an example.
    ::举一个例子。

    About how many cups are equal to 0.5 liter?
    ::有多少杯子等于0.5升?

    First, look at the table to see how cups and liters are related. You can see that 1 cup is approximately 0.24 liter.
    ::首先,看看桌子,看看杯子和升数是如何关联的。你可以看到一个杯子大约0.24升。

    Now, because you are going from a metric unit to a customary unit, you will need to divide the given value by the metric  equivalent  from the table. Keep in mind that 0.24 is approximately 0.25, and 0.5 divided by 0.25 is equal to 2.
    ::现在,由于你正在从一个计量单位到一个习惯单位,你需要将给定值除以表中的等值。记住0.24大约为0.25,0.5除以0.25等于2。

    0.5 ÷ 0.24 ≈ 2

    The answer is there are approximately 2 cups in 0.5 liter.
    ::答案是0.5升里有大约2个杯子。

    Remember that this answer is not exact! You’re just looking to get a general sense for how the two systems of measurement are related.
    ::记住这个答案并不准确! 你只是希望对两种测量系统之间的关系有一般的认识。

    Here is another example.
    ::下面是另一个例子。

    4 kilograms is equal to about how many  pounds ?
    ::4公斤等于多少磅吗?

    First, look at the table to see how pounds and kilograms are related. You can see that 1 pound is approximately 0.45 kilograms.
    ::首先,看看桌子,看看体重和公斤之间有什么关联。你可以看到,1磅约为0.45公斤。

    Now, because you are going from a metric unit to a customary unit, you will need to divide the given value by the metric equivalent from the table. Keep in mind that 0.45 is approximately 0.5, and 4 divided by 0.5 is equal to 8.
    ::现在,由于您正在从一个公制单位到一个习惯单位, 您需要将给定值除以表中的等值。 请注意, 0. 45 约为 0. 5, 4 除以 0.5 等于 8 。

    4 ÷ 0.45 ≈ 8

    The answer is there are approximately 8 pounds in 4 kilograms.
    ::答案是大约4公斤有8磅重。

    Examples
    ::实例

    Example 1
    ::例1

    Earlier, you were given a problem about Billy and his trip to Canada.
    ::早些时候,你得到一个问题 关于比利和他去加拿大的旅行。

    He noticed a sign that said “maximum 50 km/h” and he wonders what 50 kilometers per hour is in miles per hour.
    ::他注意到一个标语说“最大50公里/小时”,他想知道每小时50公里是每小时多少英里。

    First, Billy should look to see how miles and kilometers are related. He should notice that 1 mile is approximately 1.61 kilometers.
    ::首先,比利应该看看英里和公里之间的关联。他应该注意到1英里大约是1.61公里。

    Now, because he is going from a metric unit to a customary unit, he will need to divide the given value by the metric equivalent. He should keep in mind that 1.61 is approximately 1.6, and 50 divided by 1.6 is equal to about 31.
    ::现在,由于他正在从一个计量单位变成一个习惯单位,他需要将给定值除以公吨等值。 他应该记住1.61是大约1.6,50除以1.6等于大约31。

    50 ÷ 1.61 ≈ 31

    The answer is that 50 kilometers per hour is equal to approximately 31 miles per hour. This is a typical speed limit for a residential area.
    ::答案是每小时50公里等于每小时约31英里,这是住宅区典型的速度限制。

    Example 2
    ::例2

    12 teaspoons is equal to about how many milliliters?
    ::12个茶匙等于多少毫升?

    First, look at the table to see how teaspoons and milliliters are related. You can see that 1 teaspoon is approximately 4.93 milliliters.
    ::首先,看看桌子,看看茶匙和毫升是如何关联的。你可以看到一个茶匙大约是4.93毫升。

    Now, because you are going from a customary unit to a metric unit, you will need to multiply the given value by the metric equivalent from the table. Keep in mind that 4.93 is approximately 5, and 12 times 5 is equal to 60.
    ::现在,由于你正在从一个习惯单位变成一个公制单位,你需要将给定值乘以表中的等值。记住4.93大约是5,12乘以5等于60。

    12 × 4.93 ≈ 60

    The answer is there are approximately 60 milliliters in 12 teaspoons.
    ::答案是,12个茶匙里大约有60毫升。

    Example 3
    ::例3

    4 gallons is equal to about how many liters?
    ::4加仑等于多少升?

    First, look at the table to see how gallons and liters are related. You can see that 1 gallon is approximately 3.79 liters.
    ::首先,看看桌子,看看加仑和升水之间是如何关联的。你可以看到,1加仑大约是3.79升。

    Now, because you are going from a customary unit to a metric unit, you will need to multiply the given value by the metric equivalent from the table. Keep in mind that 3.79 is approximately 3.75, and 4 times 3.75 is equal to 15.
    ::现在,由于你正在从一个习惯单位变成一个公制单位,你需要将给定值乘以表中的等值。记住3.79大约是3.75,4乘以3.75等于15。

    4 × 3.79 ≈ 15

    The answer is there are approximately 15 liters in 4 gallons.
    ::答案是,4加仑有大约15升。

    Example 4
    ::例4

    60 centimeters is equal to about how many feet?
    ::60厘米等于多少英尺?

    First, look at the table to see how feet and centimeters are related. You can see that 1 foot is approximately 30.48 kilograms.
    ::首先,看看桌子,看看脚和厘米之间有什么关联。你可以看到,一英尺大约30.48公斤。

    Now, because you are going from a metric unit to a customary unit, you will need to divide the given value by the metric equivalent from the table. Keep in mind that 30.48 is approximately 30, and 60 divided by 30 is equal to 2.
    ::现在,由于你正在从一个公制单位到一个习惯单位,你需要将给定值除以表中的等值。记住30.48约为30,60除以30等于2。

    60 ÷ 30.48 ≈ 2

    The answer is there are approximately 2 feet in 60 centimeters.
    ::答案是,60厘米内有大约2英尺。

    Example 5
    ::例5

    3 cups is equal to about how many liters?
    ::3个杯等于多少升?

    First, look at the table to see how cups and liters are related. You can see that 1 cup is approximately 0.24 liter.
    ::首先,看看桌子,看看杯子和升数是如何关联的。你可以看到一个杯子大约0.24升。

    Now, because you are going from a customary unit to a metric unit, you will need to multiply the given value by the metric equivalent from the table. Keep in mind that 0.24 is approximately 0.25, and 3 times 0.25 is equal to 0.75.
    ::现在,由于您正在从一个习惯单位变为一个公制单位, 您需要将给定值乘以表中的等值。 请注意, 0. 24 大约是0. 25, 3乘以0. 75 , 3 乘以0. 25 等于 0. 75 。

    3 × 0.24 ≈ 0.75

    The answer is there is approximately 0.75 liter in 3 cups.
    ::答案是,在三个杯子里大约有0.75升。

    Review
    ::回顾

    Estimate a metric equivalent for the following customary measurements.
    ::估计以下习惯测量的计量值相当于一个计量值。

    1. 5 cups to liters
      ::5个杯至升
    2. 5 yards to meters
      ::5码至5米
    3. 6 inches to mm
      ::6英寸至毫米
    4. 15 pounds to kg
      ::15磅至公斤
    5. 1 cup to liters
      ::1个杯,升至1升
    6. 4 miles to km
      ::4英里至公里
    7. 5 feet to cm
      ::5英尺至厘米
    8. 12 feet to cm
      ::12英尺至厘米
    9. 8 inches to mm
      ::8英寸至毫米
    10. 28.5 ounces to grams
      ::28.5 盎司至克
    11. 11.75 inches to millimeters
      ::11.75英寸至毫米
    12. 8 quarts to liters
      ::8 夸特至升
    13. 15 pounds to kilograms
      ::15磅至公斤

    Solve the following problems.
    ::解决以下问题。

    1. To join the swim team, Jessica swam every day. The distances she swam for the first four days were as follows: 1.65 km, 1,750 m, 185,000 cm, 1,950,000 mm. If the pattern continues, how many kilometers will she swim on the fifth day?
      ::参加游泳队,Jessica每天游泳。她头四天游泳的距离如下:1.65公里,1 750米,185 000厘米,1 950 000毫米。如果这种模式继续下去,她第五天会游泳多少公里?
    2. Mrs. Roth is moving to a new apartment. She can lift exactly 22.5 kg. Which of the following objects can she lift: box of books (23,500 g), statue (2,450,000 cg), computer (2,550,000 mg), potted plant (22.55 kg)?
      ::Roth夫人正在搬进一个新的公寓,她可以完全举起22.5公斤。她可以举起下列哪些物体:书箱(23 500克)、雕像(2 450 000克)、计算机(2 550 000毫克)、陶工厂(22.55公斤)?

    Review (Answers)
    ::回顾(答复)