STAT homework

Use Table II of the Appendix to find the proportion of the normal curve that is

1)       Between a z-score of .50 and the mean

2)       Between a z-score of 1.50 and the mean

3)      At or below a z-score of 1.20

4)      At or above a z-score of -1.60

5)      Between the z-scores of -1.00 and .50

6)      Between the z-scores of -1.65 and .50

7)      Between the z-scores of -1.96 and .50

8)      The lengths of time bank customers must wait for a teller are normally distributed, with a mean of 3 minutes and a standard deviation of 1 minute.

1. What proportion of bank customers waits between 3 and 4.5 minutes

1.  What percentage wait more than 4 minutes?

1. What proportion waits between 2 and 3.5 minutes?

1. What percentage wait less than 1 minute?

9)  A real estate agent records the ages of 50 randomly selected home buyers in her sales area.  The mean

        age is 38 years, with a sample standard deviation of 10 years.

1. Find a 99% confidence interval for the population mean age.