statistics
posted by Anonymous .
A sample of 25 different payroll depts. found that the employees worked an average of 310.3 days a year with a standard deviation of 23.8 days. What is the 90% confidence interval for the average days worked by employees in all payroll departments?

statistics 
PsyDAG
90% = mean ± 1.645 SEm
SEm = SD/√n
Respond to this Question
Similar Questions

statistics
The average time in data to process orders received by a metal fabrication company is to be estimated. A sample of 20 orders is randomly selected from a total of 200 orders processed over a 6 month period and the sample mean is 5.4 … 
Statistics
8.11) For the manufacturing plant discussed in Exercise 8.10, the union president and the human resources director jointly select a simple random sample of 36 employees to engage in a discussion with regard to the company’s work … 
Statistics
For the manufacturing plant discussed in Exercise 8.10, the union president and the human resources director jointly select a simple random sample of 36 employees to engage in a discussion with regard to the company’s work rules … 
Statistics
For the manufacturing plant discussed in Exercise 8.10, the union president and the human resources director jointly select a simple random sample of 36 employees to engage in a discussion with regard to the company’s work rules … 
statistics
a study found that the average time it took a person to find a new job was 130 days. If a sample of 36 job seekers was surveyed, find the 95% confidence interval of the mean. Assume the standard deviation of the sample is 12 days. 
Statistics
The average annual salary of employees at Wintertime Sports was $28,750 last year. This year the company opened another store. Suppose a random sample of 18 employees had an average annual salary of $25,810 with standard deviation … 
Probability and Statistics
For questions 1 5 use confidence intervals to test the hypothesis. 1) A light bulb producing company states that its lights will last an average of 1200 hours with a standard deviation of 200 hours. A sample of 100 light bulbs from … 
statistics
3. The personnel director of a corporation will study the overtime work during the previous year for the 2,575 clerical workers. A sample of 100 of these workers will be chosen at random from the files. The average and the standard … 
statistics
The number of vacation days taken by employees of a company is normally distributed with a mean of 14 days and a standard deviation of 3 days. For the next employee, what is the probability that the number of days of vacation taken … 
statistics
The number of vacation days taken by employees of a company is normally distributed with a mean of 14 days and a standard deviation of 3 days. For the next employee, what is the probability that the number of days of vacation taken …