章节大纲

  • 常规

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  • 理解可能性

    In This Lesson
    ::在本课程中

    You will understand how to calculate and classify the likelihood of events using probability .
    ::您将了解如何使用概率计算和分类事件的可能性。

    Probability is the likelihood of a particular outcome occurring. The probability of an outcome can be expressed in three different ways : as a ratio, a percentage or a decimal. When determining a  probability, you need to consider the sample space , or the set of all possible outcomes . There are two types of probability – theoretical and experimental. Theoretical probability is what is predicted to  happen given the the possible number of outcomes and sample space. Experimental probability is what actually  happens after an experiment is performed. 
    ::概率是特定结果发生的可能性。 结果的概率可以用三种不同的方式表示:比率、百分比或小数点。在确定概率时,你需要考虑样本空间,或所有可能的结果。有两种概率 — — 理论和实验。理论概率是预测的结果和样本空间的可能数量。实验概率是实验进行后实际发生的情况。

     

    It’s in the Bag
    ::写在袋子里

    Imagine there are 8 marbles in a paper bag, 2 are green, 3 are red, 2 are blue, and 1 is black. As you take marbles out of the bag, the probability of getting a certain color changes.
    ::想象一下纸袋里有8个弹珠,2个是绿色,3个是红色,2个是蓝色,1个是黑色。当你从袋子里取弹珠时,有某种颜色变化的可能性。

    Use the interactive to take marbles out of the bag and see how the probability of getting a certain color next changes.
    ::使用交互程序从包中取出弹珠, 并查看下一颜色的概率如何变化 。

     

     

    INTERACTIVE
    It's In The Bag Pt.1
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    • Drag the marbles in and out of the bag to see the different probabilities.
      ::将大理石从袋子里拖出来 以观察不同的概率
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    The probability or likelihood of an outcome is always between 0 and 1, where a probability of 0 represents an outcome that is impossible (0% chance of happening) and a probability of 1 represents an outcome that is certain to occur (100% chance of happening).
    ::结果的概率或可能性总是在0到1之间,其中0的概率代表不可能的结果(发生概率为0%),而1的概率代表必然发生的结果(发生概率为100%)。

    The halfway point is a probability of 0.5 which represents outcomes that are equally likely and unlikely  to occur (50% chance). Any probability between 0 and 0.5 is considered unlikely and anywhere between 0.5 and 1 is considered likely . The closer to 0 the more unlikely an outcome will occur and the closer to 1 the more likely an outcome will occur.
    ::中间点是0.5的概率,表示结果同样有可能和不太可能发生(50%的概率 ) 。 任何0到0.5之间的概率都被认为是不太可能的,大约在0.5到1之间。 越接近0,结果就越不可能发生,而接近1的结果就越有可能发生。

    Probability scale ranging from impossible (0) to certain (1).
    Likelihood

     

    It’s in the Bag, Part 2
    ::它在包里,第2部分

    Recall the previous scenario: t here are  8  marbles in the bag:  2  are green,  3 are red,  2 are blue, and  1 is black. As you  take marbles out of the bag, the probability of  getting a certain color changes.
    ::回顾前一种情况:包里有8个弹珠:2个是绿色,3个是红色,2个是蓝色,1个是黑色。当你从包里取弹珠时,有某种颜色变化的可能性。

    • Compare how the probability of each outcome is affected before and after you take out a marble.
      ::比较每个结果的概率 在你拿出大理石之前和之后 如何受到影响。
    • Is anything 100% or 0% likely?
      ::百分之百或百分之零的可能吗?

     

     

    INTERACTIVE
    It's In The Bag Pt.2
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    • Drag the different colored marbles in and out of the back to see the change in probability for each color.
      ::拖曳不同的彩色弹珠进出后座以观察每种颜色的概率变化。
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    Discussion Question
    ::讨论问题

    If you pull all of the marbles out of the bag, it will give you 0 marbles out of 0 marbles, or 0/0, which is an undefined value . What does this value represent in the context of this example? for the answer!
    ::如果你把所有大理石都从包中拉出来,它会给你0大理石中的0大理石或0/0,这是一个未定义的数值。这个数值在这个例子中代表什么?答案是多少?

     

    The likelihood of something not happening is the same subtracting the probability of that  outcome  from 1.0 (or 100%).  For example , the likelihood of picking the black marble after  taking out three  other marbles would have been 1 out of 5, or 0.2.  Therefore, the likelihood of not picking a black marble would be 1 - 0.2 = 0.8.
    ::不发生某种事情的可能性与从1.0(或100%)中减去这种结果的概率相同。 例如,在取出另外三种大理石之后,摘取黑大理石的可能性为5分之一或0.2。 因此,不摘取黑大理石的可能性为1-0.2=0.8。

     

    Dart Board
    ::达达董事会

    You play a game by throwing darts onto a game board split up into squares. You win if your dart hits a blue square.
    ::你把飞镖扔到一个游戏板上 分成了方块。如果你的飞镖撞到蓝色方块,你就赢了。

    Use the interactive to explore and help answer the questions below.
    ::使用互动方式探讨并帮助回答下列问题。

     

     

    INTERACTIVE
    Dart Boards & Probabilities
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    • Click the square tiles to mark them blue.
      ::单击方格牌来标记它们蓝色 。
    • The more blue squares marked, the higher the probability of the dart hitting the squares.
      ::蓝色方形标记越大,飞镖撞击方形的概率就越高。
    • Click "Throw Dart" to throw a dart at the board.
      ::点击"发射达特" 扔飞镖在板上。
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       Summary
    ::摘要

    • Probability (or likelihood) of an outcome is always a number between 0 and 1.
      ::结果的概率(或可能性)总是0到1之间的数字。
    • Probability (or likelihood) can be expressed as a ratio, percent or decimal.
      ::概率(或可能性)可以用比率、百分比或小数点表示。