Exam 3

Warning: go here first.

Do all the problems on the computer. Make sure all your solutions are complete. Write down the sequence of commands you used (for example Stat > Basic Statistics > Descriptive Statistics ...)

We will use the WRInc data for all the problems in this exam. You do not need to check any assumptions.

Problem 1:
Find the five-number summary for Income of all employees. Find the five-number summary for the Income of the employees with a Satisfaction of 5..

Problem 2:
Find a 90% confidence interval for the mean of the Years of the employees. Find a 90% confidence interval for the mean of the Years of the employees who have an income of at least $30000.

Problem 3:
Test at the 1% level whether the mean distance is less than 2.5 miles.

Problem 4:
We randomly select an employee from WRInc
a) What is the probability that person has a Job Level of 4?
b) What is the probability that person has a Job Level of at least 3?
c) What is the probability that person has a Job Level of 4 and a Satisfaction of at most 3?
d) What is the probability that person has a Job Level of 4 or a Satisfaction of 6 but not both?

Problem 5:
Find the least squares regression line for Income by Years(=x). Draw the following graph, but with your name, in black and white and with the empty diamond as the plotting symbol, and with the text Me! in same place.

Problem 6:
For each of the following give the single expression in the Calculator command that would

a) find the sum of the incomes
b) find the number of employees with a job level of 4
c) find the number of female employees with a job level of 4
d) find the percentage of employees with between 5 and 10 years of service, rounded to 1 digit.

Problem 7:
Use MINITAB to find a random sample of size 10 of the employees, and use it to find a 90% confidence interval for the mean Income. Does your interval contain the true parameter?