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...

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

... 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 ...

... department store chain is interested in estimating the average ... closer to 0.50 that p is estimated to be ... given 14 A statistician wishes to estimate the average ...

... 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...

... normal distribution; (2) how to use Excel to select a simple random sample; (3) how to use Excel built-in functions and procedures to estimate population mean...

... taking a random sample of 18 items in an effort to estimate the population mean. ... Question 9: A researcher is interested in estimating the mean value for a ...

... 20. A business wants to estimate the true mean annual income of its customers. ... The business estimates the true population standard deviation is around ...

... up a 90% confidence interval estimating the mean... registered voters in Pennsylvania to estimate what proportion ... be 95% confident that your estimates are within ...