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Math Help - Stats help!

  1. #1
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    Mar 2010
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    Stats help!

    I have this work could anyone help? I am lost.


    A brand of breakfast cereal is available in two sizes: the weights (in
    grammes) of the edible contents, and packaging are both Normally distributed
    with the following means and standard deviations:
    Edible contents Packaging


    Small

    μ = 465, σ = 10 μ = 25, σ = 3
    Standard



    μ = 625, σ = 15 μ = 20, σ = 2
    .
    Find the probabilities that



    a randomly chosen Standard box has a total weight exceeding 640
    grammes,



    the total weight of the edible contents of 4 randomly chosen Standard
    boxes exceeds


    2450 grammes.



    the edible contents of 4 randomly chosen Small boxes weigh more
    than the edible contents of


    3 randomly chosen Standard boxes.



    the total weight of 4 randomly chosen Small boxes is more than the
    total weight of


    3 randomly chosen Standard boxes.



    the total weight of 4 randomly chosen Small boxes is more than the
    total weight of


    3 randomly chosen Standard boxes when each box also
    contains a small toy weighing exactly
    50 grammes.

    2. A factory makes both rods and copper tubes, with diameters expressed in
    centimetres. Due to variations in the manufacturing process, it is known
    that the internal diameter of a copper tube is



    N 2.2, 0.032, while the
    diameter of a rod is


    N 2.15, 0.022.



    Find the proportion of tubes with an internal diameter less than
    2



    .19cm.



    Find the proportion of rods with a diameter greater than 2.17cm



    Find the proportion of rods with a diameter between 2.17cm and
    2



    .20cm.



    A rod and tube are chosen at random. Find the probability that the
    rod will not pass through the tube.

    3. A population consists of the following five values:



    24, 26, 29, 30 and 31;
    consider sampling


    without replacement from this population.



    List all samples of size three, and compute the mean of each sample.



    Compute the mean of the distribution of sample means, and the
    population mean, and compare these two values.



    Compare and comment on the spread in the population with that in
    the sample means.


    Thanks alot!
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  2. #2
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    Please don't post more than two questions in a thread. Otherwise the thread can get convoluted and difficult to follow. It is better for forum organization and better for you to get your questions answered in a more timely manner if you start new threads as necessary for remaining questions. eg. If you have five questions, post two of them in two threads and start a new thread for the remaining one etc.

    And if the question has more than two parts to it, it is best to post only that question and its parts in the thread and start a new thread for other questions.

    Furthermore, the wording of this question strongly suggests that it might count towards your final grade. MHF policy is to not knowingly help with such questions.

    Thread closed.
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