Use Table (http://www.itl.nist.gov/div898/handbook/eda/section3/eda3671.htm) to find the proportion of the normal curve that is
1) Between a z-score of .60 and the mean
2) Between a z-score of 1.60 and the mean
3) At or above a z-score of 1.30
4) At or below a z-score of 1.30
5) At or below a z-score of -1.00
6) At or above a z-score of -1.00
7) Between the z-scores of -1.00 and .60
8) Between the z-scores of -1.50 and .65
9) Between the z-scores of -1.96 and .25
1. What percentage of a normal distribution is within 2 standard deviations of the mean? (Select the closest answer)
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.
2. What proportion of bank customers waits between 2 and 3.5 minutes
•a. What percentage wait more than 4 minutes?
•b. What proportion waits between 1 and 2.5 minutes?
•c. What percentage wait less than 1 minute?
3. To estimate the medical charges for an appendectomy Blue Star Insurance has data from a random sample of 70 patients. The sample mean cost is $510, with a sample standard deviation of $70
Construct a 95% confidence interval for the population mean cost.
4. We are 95% confident that the populations mean costs of patients’ medical charges for an appendectomy through Blue Star Insurance range is between _____________ and ________________.
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.
Find a 99% confidence interval for the mean age.