For Problem 1 and 2: A random sample of 16 graduates of a certain secretarial school...
A random sample of 16 graduates of a certain secretarial school typed an average of 85 words per minute with a standard deviation of 8 words per minute. Assume that the number of words typed per minute of a randomly selected graduates follows a normal distribution . 1. Construct a 95% confidence interval to estimate the average number of words typed by all graduates of this school. Remember to state the assumptions and interpret the result. Following R commands may...
2. A random sample of 100 graduates of a certain secretarial school typed an average of 90 words per minute with a sample standard deviation (s) of 10 words per minute. We assume a normal distribution for the number of words typed per minute. (a) (4pts) Find a 95% confidence interval for the average number of words t yped per minute of all graduates of this school. (b) (3pts) Suppose the population standard deviation (o) is exactly 10 words per...
A random sample of 16 graduates of a certain secretarial school typed an average of 76.1 words per minute with a standard deviation of 7.3 words per minute. Assuming a normal distribution for the number of words typed per minute, find a 90% confidence interval for the average number of words typed by all graduates of this school, Click here to view.page 1 of the standard normel distribution table, Click here to view page 2 of thee standard normal distribution...
A random sample of 18 graduates of a certain secretarial school typed an average of 80.2 words per minute with a standard deviation of 7.9 words per minute. Assuming a normal distribution for the number of words typed per minute, find a 99% confidence interval for the average number of words typed by all graduates of this school. Click here to view page 1 of the standard normal distribution table. Click here to view page 2 of the standard normal...
Question 9 (1 point) For a random sample of 18 recent business school graduates beginning their first job, the mean starting salary was found to be $43,500, and the sample standard deviation was $5,500. Assuming the population is normally distributed, find the margin of error of a 95% confidence interval for the population mean.
For a random sample of 16 recent business school graduates beginning their first job, the mean starting salary was found to be $39,500, and the sample standard deviation was $8,500. Assuming the population is normally distributed, calculate the lower confidence limit (LCL) of the population mean with a 0.05.
Question 10 (1 point) For a random sample of 15 recent business school graduates beginning their first job, the mean starting salary was found to be $35,500, and the sample standard deviation was $7,500. Assuming the population is normally distributed, calculate the lower confidence limit (LCL) of the population mean with a -0.01. Your Answer:
A random sample of 85 group leaders, supervisors and similar personnel at General Motors revealed that, on average, they spent 6.5 years in a particular job before being promoted. The standard deviation of the sample was 1.7 years. Construct a 95% confidence interval. Explain which words in the problem indicate a z-distribution or a t-distribution (choose one). Show how to calculate the confidence interval using Excel or typing out the equation (such as for proportions). The purpose is to identify...
2. A sample of 60 night school students had an average age of 25.3 years. Use this information and a population variance of 16 to find a a. 95% confidence interval estimate for the population mean (2 pts) b. 99% confidence interval estimate for the population mean (2 pts) c. Redo part a) assuming 16 is the sample variance. (2 pts)
A random sample of 16 items is drawn from a population whose standard deviation is unknown. The sample mean is = 890 and the sample standard deviation is s= 15. Use Appendix D to find the values of Student's t. (a) Construct an interval estimate of u with 95% confidence. (Round your answers to 3 decimal places.) The 95% confidence interval is from O t o D (b) Construct an interval estimate of u with 95% confidence, assuming that s=...