Res 341 Week 5 E-Text

.State the main points of the Central Limit Theorem for a mean.

 

.Why is population shape of concern when estimating a mean? What does sample size have to do

  

with it?

 

.A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was weighed on a very accurate scale. The results in grams were

3.087     3.131     3.241   3.241   3.270   3.353    3.400   3.411    3.437    3.477

 

(a) Construct a 90 percent confidence interval for the true mean weight. (b) What sample size would be necessary to estimate the true weight with an error of +_ 0.03 grams with 90 percent confidence? (c) Discuss the factors which might cause variation in the weight of Tootsie Rolls during manufacture. 

 

.In 1992, the FAA conducted 86,991 pre-employment drug tests on job applicants who were to be engaged in safety and security-related jobs, and found that 1,143 were positive. (a) Construct a 95 percent confidence interval for the population proportion of positive drug tests. (b) Why is the normality assumption not a problem, despite the very small value of p?