1) A state meat inspector in Iowa has been given the assignment of estimating the mean net weight of packages of ground chuck labeled "3 pounds". Of course he realizes that the weights cannot be precisely 3 pounds. A sample of 36 packages reveals the mean weight to be 3.01 pounds, with a standard deviation of 0.03 pounds.
A) What is the estimated population mean.
B) Determine a 95 percent confidence interval for the population mean.

2. A study of a company's practice regarding the payment of invoices revealed that an invoice was paid an average of 20 days after it was received. The standard deviation equaled five days. Assuming that the distribution is normal, what percent of the invoices were paid within 15 days of receipt?

3. A national manufacturer of unattached garages discovered that the distribution of the lengths of time it takes two construction workers to erect the Red Barn model is approximately normally distributed with a mean of 32 hours and a standard deviation of 2 hours. What percent of the garages take between 30 and 34 hours to erect?

Solution Preview

1.

A) Estimate of population mean = sample mean according to central limit theorem. Hence answer is 3.01

B) 95% confidence interval for mean

According to central limit theorem, the sample mean is normally distributed with mean = population mean and standard
deviation = sample sd/sqrt(n) = 0.03/sqrt(36) = 0.03/6 = 0.005

z ...

Solution Summary

The solution examines estimating the population mean and determining the normal distribution. The percent of invoices paid on time is determined.

... With this background estimating the population mean should ... confidence interval (an interval estimate) for a ... The solution estimates and interprets a population...

... closer to 0.50 that p is estimated to be ... store chain is interested in estimating the average ... size, degrees of freedom, one-sided confidence interval estimate. ...

... several methods, in sequence, of estimating the population... a single sample, and the estimated variance is ...population variance B.pooled estimate of population...

... Standard error of estimate is the standard deviation of ... meat inspector in Iowa is estimating the mean... Step 1: Estimated population mean is equal to the sample ...

... chain is interested in estimating the average ... sample standard deviation to estimate the population... n > 15 For normal population distributions, the sampling ...

... The sample mean of 3.3 hours estimates the unknown ... vals that would include the parameter being estimated. ... a small standard error of estimate, indicating that ...

... in Iowa has been given the assignment of estimating the mean... a. What is the estimated population mean? X An unbiased estimate of population mean is given by ...

... Interval Construct/Estimate a Population Mean/Estimate the Value of a ... b) No prior estimates are used? ... Data Estimate of True Proportion 0.5 Sampling Error 0.025 ...

... $99 $100 $98 $104 $126 Assume a normal distribution and develop a 95% confidence interval estimate of the population mean cost for a prescription of Zocor. ...

... and draw a dotplot for sampling distribution of the ... that the sample mean will equal the population mean. ... the sampling error made in estimating the population...