Salary data from two random samples of high school teachers are shown to the right. Also shown are the population Sample mean Sample size Population standard standard deviations. deviation State A $50,574 State B $46,966 36 47 $6,711 $7,218 a. Construct a 90% confidence interval to estimate the difference in the average salaries of the high school teachers in these two states. b. Based on the results in part a, can you conclude that a difference exists in the average salaries? a. Let population 1 = the salaries of the high school teachers in State A and population 2 = the salaries of the high school teachers in State B. The confidence interval is ($$ (Round to the nearest dollar as needed.)

Suppose we wish to study the average income of Cactus Club customers, so we plan to conduct a research project with a 95% confidence level. We need our range of error (E) to be no greater than $500. Based on our past experience, we estimate the sample standard deviation to be $5,000. What sample size do you need in order to conduct the research? Select one: a. 372 b. 784 c. 824 d. 385 e. 196

Answer.

Part b. Please show TI 84 steps

Which type of confidence interval should you use in this situation? A sample of 25 different payroll departments found that the employees worked an average of 310.3 days a year with a standard deviation of 23.8 days. The distribution is approximately normally distributed. Find the 90% confidence interval for the average days worked of all payroll departments.   Question 2 options:   1)  a confidence interval for the mean using a table value from the standard normal distribution.   2)  a confidence interval for the mean using a table value from the t distribution.   3)  a confidence interval for a proportion using a table value from the standard normal distribution.   4)  a confidence interval for proportion using a table value from the t distribution.   5)  none of the above.

MC Qu. 10-64 Sales at a fast-food restaurant average... Sales at a fast-food restaurant average $6,000 per day. The restaurant decided to introduce an advertising campaign to Increase daily sales. In order to determine the effectiveness of the advertising campaign, a sample of 49 day's sales were taken. The sample showed average daily sales of $6,300. From past history, the restaurant knew that its population standard deviation is about $1,000. If the level of significance is 0.01, have sales increased as a result of the advertising campaign? Multiple Choice Fail to reject the null hypothesis. Reject the null hypothesis and conclude the mean is higher than $6,000 per day. Reject the null hypothesis and conclude the mean is lower than $6,000 per day. Reject the null hypothesis and conclude that mean equal to $6,000 per day.

9 The standard error of the mean is, a 0.881       b 0.735       c 0.612       d 0.510