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Thread: Population mean, standard deviation

  1. #1
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    Population mean, standard deviation

    Time lost due to employee absenteeism is an important problem for many companies. The human resources department of Western Electronics has studied the distribution of time lost due to absenteeism by individual employees. During a one-year period, the department found a mean of 21 days and a standard deviation of 10 days based on data for all the employees.
    1. If many samples of 36 employees each are taken and sample means computed, a distribution of sample means would result. What would be the mean, standard deviation and shape of the distribution of sample means for samples of size 36? Give reasons for your answers.
    2. A group of 36 employees is selected at random to participate in a program that allows a flexible work schedule, which the human resources department hopes will decrease the employee absenteeism in the future. What is the probability that the mean for the sample of 36 employees randomly selected for the study would exceed 25 days?


    Can someone help me? solving this probelm a and b. thank you

  2. #2
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    Hmmm... All that is required is reading the defintion of the distribution of a sample mean.

    The sample mean is an unbiased estimator, so its expected value is...?

    The sample size is convenitnely selected as a perfet square. That's so sweet. population standard deviation divided by ...?

  3. #3
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    Quote Originally Posted by san005 View Post
    Time lost due to employee absenteeism is an important problem for many companies. The human resources department of Western Electronics has studied the distribution of time lost due to absenteeism by individual employees. During a one-year period, the department found a mean of 21 days and a standard deviation of 10 days based on data for all the employees.
    1. If many samples of 36 employees each are taken and sample means computed, a distribution of sample means would result. What would be the mean, standard deviation and shape of the distribution of sample means for samples of size 36? Give reasons for your answers.
    2. A group of 36 employees is selected at random to participate in a program that allows a flexible work schedule, which the human resources department hopes will decrease the employee absenteeism in the future. What is the probability that the mean for the sample of 36 employees randomly selected for the study would exceed 25 days?
    Can someone help me? solving this probelm a and b. thank you
    I don't see problem a and b - where are those?

    Please share your work with us, indicating exactly where you are stuck - so that we may know where to begin to help you.
    Last edited by Subhotosh Khan; 02-05-2012 at 01:26 PM.
    “... mathematics is only the art of saying the same thing in different words” - B. Russell

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