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Math Help - Mean, Samples, and Standard Deviation. Please Help!!

  1. #1
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    Mean, Samples, and Standard Deviation. Please Help!!

    Hey all so I am in college statistics and this is just not clicking what so ever and I am really freaking out. No i am not trying to get answers, but steps. I am in a class of 300 so our professor goes through slides very quickly and its difficult for me to keep up and understand. We started a new section and I really need to know how to do these for the future test. I have been to office hours and he just doesn't seem to care and I am really worried about my grade. If any of you know how to solve these and can show me the rules or steps you have know idea how greatly appreciated that would be.

    Thank you so much.

    1. A measurement is normally distributed with mean=21.5 and standard deviation=6.1.
    (a) The mean of the sampling distribution of the sample mean for samples of size 15 is : ____
    (b) The standard deviation of the sampling distribution of the sample mean of size 15 is : ____

    2. For patients who have been given a diabetes test, blood-glucose readings are approximately normally distributed with mean 129 mg/dl and a standard deviation 10 mg/dl. Suppose that a sample of 3 patients will be selected and the sample mean blood-glucose level will be computed.

    According to the empirical rule, in 95 percent of samples the SAMPLE MEAN blood-glucose level will be between the lower-bound of ______ and the upper-bound of _________.

    3. A biologist claims that nearly 45 percent of all Americans have brown eyes. A random sample of n=55. Mizzou students found 27 with brown eyes. Give the numerical value of the statistic sample proportion.

    sample proportion= _____

    4. Nationwide, 65 percent of persons taking a certain professional certification exam pass. Consider, for a samples of 200, the sampling distribution of sample proportion.
    (a) The mean of the sampling distribution of sample proportion is:_____
    (b) The standard deviation of the sampling distribution of the sample proportion is:_______

    5. A random sample of 80 Mizzou students showed that 44 had driven a car during the day before the survey was conducted. Suppose that we are interested in forming a 95 percent confidence interval for the proportion of all Mizzou students who drove a car the day before the survey was conducted.
    Where appropriate, express your answer as a proportion (not a percentage).
    (a) The estimate is:____
    (b) The standard error is:____
    (c) The multiplier is:____

    6.A recent survey showed that among 100 randomly selected college seniors, 20 plan to attend graduate school and 80 do not. Determine a 99 % confidence interval for the population proportion of college seniors who plan to attend graduate school.

    99% Cl:_____ to _______
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  2. #2
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    Re: Mean, Samples, and Standard Deviation. Please Help!!

    Hey raytiarabrown.

    Can you show us any attempts (partial or otherwise) and your method of thinking? It's a lot easier for us to help you if you do these things.
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