Exam 8: Statistical Inference: Estimation for Single Populations

A researcher wants to estimate the proportion of manufacturing companies that use the six sigma method.For this purpose,she will take a random sample of 50 manufacturing companies and find out how many of them use this method.She estimates that the proportion will be anywhere from 0.4 to 0.55.Of all these proportions,which one would produce the widest 95% confidence interval for the population proportion?

Given the error we are willing to tolerate,the sample size is determined by the meanµ of the population and the confidence level.

The table t value associated with the upper 5% of the t distribution and 14 degrees of freedom is _______.

In determining the interval estimates for a population proportion using the sample proportion,it is appropriate to use the z-distribution.

A random sample of 64 items is selected from a population of 400 items.The sample mean is 200. The population standard deviation is 48.From this data,a 95% confidence interval to estimate the population mean can be computed as _______.

A researcher wants to estimate the proportion of manufacturing companies that use the six sigma method.For this purpose,she takes a random sample of 50 manufacturing companies and finds out that 28 of them employ this method.The 95% confidence interval for the proportion of manufacturing companies that use six sigma is ______.

You need to determine the population variance of the diameters of a specialized electronic component you need to use for a new product.Other studies indicate that the diameters of this product are roughly normally distributed.You take a sample of 15 units and find out that the sample average diameter is 0.24 mm,and the sample standard deviation is 0.2 mm.What is the 95% confidence interval for the population variance?

A large trucking company wants to estimate the proportion of its tracker truck population with refrigerated carrier capacity.A random sample of 200 tracker trucks is taken and 30% of the sample have refrigerated carrier capacity. The 90% confidence interval to estimate the population proportion is _______.