*EXPERT* *EXCEL*QNT/275: Statistics For Decision Making
LUUP777
Week4ExercisePost.xlsx1
A sample of 100 items has a population standard deviation of 5.9 and a mean of 32. Construct a 95 percent confidence interval for μ.
2
At the end of 1990, 1991, and 1992, the average prices of a share of stock in a portfolio were $34.75, $34.65, and $31.25 respectively. To investigate the average share price at the end of 1993, a random sample of 75 stocks was drawn and their closing prices on the last trading day of 1993 were observed with a mean of 33.78 and a standard deviation of 14.25. Estimate the average price of a share of stock in the portfolio at the end of 1993 with a 90 percent confidence interval.
3
A research study investigated differences between male and female students. Based on the study results, we can assume the population mean and standard deviation for the GPA of male students are µ = 3.3 and σ = 0.3. Suppose a random sample of 1200 male students is selected and the GPA for each student is calculated. Find the interval that contains 90 percent of the sample means for male students.
4
A manufacturing company measures the weight of boxes before shipping them to the customers. If the box weights have a population mean of 80 lb and standard deviation of 6 lb, respectively, then based on a sample size of 100 boxes, what is the probability that the average weight of the boxes will exceed 83 lb?
5
A random sample of size 100 is taken from a population with mean 64 and standard deviation 5.2. Find P(x bar < 60).
