PDA

View Full Version : Population mean, standard deviation

san005
01-23-2012, 02:39 PM
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.
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.
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

tkhunny
01-23-2012, 07:45 PM
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 ...?

Subhotosh Khan
02-05-2012, 02:17 PM
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.
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.
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.