An economist is interested in studying the incomes of consumers in a particular region. The population standard deviation is known to be $1,000. A random sample of 50 individuals resulted in an average income of $15,000. What is the upper end point in a 99% confidence interval for the average income?

A sample of 16 ATM transactions shows a mean transaction time of 67 seconds with a standard deviation of 12 seconds. State the hypotheses to test whether the mean transaction time exceeds 60 seconds.

In a statistical test, we

Given a population standard deviation of 75 and a margin of error of 16, determine the minimum sample size needed at a 95% confidence level.

For the following 6 questions, use this information: A medical investigation claims that the number of infections per week at a hospital is 16.3. A random sample of 10 weeks had a mean number of 17.7 infections. The sample standard deviation is 1.8 and the significance level is 0.05. What is the null hypothesis?

Which of the following decisions could result in a Type II error for a test?

A researcher thinks that if expectant mothers take vitamins, the birth weight of the baby will increase. The average birth weight of the population is 8.6 pounds. State the null and alternative hypotheses.

From a sample of 400 items, 14 are found to be defective. The point estimate of the population proportion defective will be:

How should we interpret our results?

Find the critical value for  t 0 for a left-tailed test with  α = 0 . 01   a n d     n = 14