Normal Distribution 1.

The weekly incomes of a large group of middle managers are normally distributed with a population mean of $1,000 and a population standard deviation of $100. What is a. the zscore of $1,100? b. the area to the right of the zvalue ?

2. An automaker does quality control tests on the paint thickness at different points on its car parts since there is some variability in the painting process . A certain part has a target thickness of 2 mm . A random sample of 100 points were taken. The distribution of thicknesses on this part is normally distributed with mean of 2mm and standard deviation of 0.5. What is the probability that the mean is less than 1.9mm ?

3. A automotive engineer wants to estimate the cost of repairing a car that experiences a a 25 MPH headon collision. He crashes 24 cars , and the average repair is $11,000 . The standard deviation of the 24- car sample is $2,500. What is the lower and upper limits of a 95% confidence interval?