The average salary of 25 random employees in a certain financial sector was 3400 USD. The sample standard deviation was 540 USD. We are interested in the 90% confidence interval for the population mean. What is the value of the margin of error? Select one: O a. 153.99 O b. 92.39 O c. 184.79 O d. 123.19

In a recent sample of 89 used cars sales costs, the sample mean was $6,225 with a standard deviation of $3,151. Assume the underlying distribution is approximately normal.   Which distribution should you use for this problem? Construct a 95% confidence interval for the population mean cost of a used car.

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

In a survey, 41 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $36 and standard deviation of $4. Find the margin of error for a 95% confidence level.

A survey of 73 randomly selected homeowners finds that they spend a mean of $74 per month on home maintenance. Construct a 95% confidence interval for the mean amount of money spent per month on home maintenance by all homeowners. Assume that the population standard deviation is $16 per month. Round to the nearest cent.

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.

A random sample of 64 shoppers showed that they spend an average of $27.31 per visit at the Sunday Mornings Bookstore. The standard deviation of the population is $2.14. Find the 90% confidence interval of the true mean. Please include all work showing how you found your answer.

Researchers studied the mean egg length (in millimeters) for a bird population. After taking a random sample of eggs, they obtained a 95% confidence interval of (45,60). What is the value of the margin of error? Choose the correct answer below. A. 15 mm B. 52.5 mm O c. 7.5 mm O D. 1.96

Christina wants to know the true average number of pages in a typical textbook. She randomly selects 196 books, and they have an average of 161 pages. Calculate a 90.3% confidence interval if you are given that the standard deviation for a single book is 75 pages.

In a survey 12 people were asked how much they spent on their child's last birthday gift.  the results were roughly bell shaped with a mean of $30 and a standard deviation of $9. Find the margin of error at 80% confidence level.