In: Statistics and Probability
A large corporation has a plant that has started a pilot program to give stock options for its assembly line workers as part of their benefits package. The corporation would like to determine if the mean quality score for this plant exceeds the current average quality measure of 82. A random sample of 50 production units is selected from this plant and the quality scores for these units are obtained. The sample mean score for these units is 86 with a sample s.d. of 7.2.
(a) Construct a 90% confidence interval for the mean score of this plant.
(b) Use this data as a preliminary sample to determine the sample size required to estimate the mean quality score under this program to within +/- 2.0 with 95% confidence.
(c) Construct a 90% confidence interval for the s.d. of quality scores.
(a)
90% confidence interval for the mean score of this plant. : ( 84.293 , 87.707 )
(b)
We are given :
(c)
(1-)% confidence interval for s.d is :
90 % confidence interval is :