probability

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A random experiment of tossing a die twice is performed. Random variable X on this
sample space is defined to be the sum of two numbers turning up on the toss. Find the
discrete probability distribution for the random variable X and compute the corresponding
mean and standard deviation.

  • probability -

    36 possibilities
    number of times sum
    1 * 2 = 2
    2 * 3 = 6
    3 * 4 = 12
    4 * 5 = 20
    5 * 6 = 30
    6 * 7 = 42
    5 * 8 = 40
    4 * 9 = 36
    3 * 10= 30
    2 * 11= 22
    1 * 12= 12
    -----------
    36 and 252
    mean = 252/36 = 7
    go ahead and compute sigma

  • probability -

    A dictionary contains 80,000 words, of which a certain student knows 30,000. If 100 of the 80,000 words are selected at random from the dictionary without replacement, find the probability:the student knows exactly 40 of the 100 words

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