Question

10          In a normal distribution find the proportion of area between the z scores of -1.64 and 0.55.

11          In a normal distribution find the z score(s) that cuts off the middle 70% of the scores.

4. If families in a small local community have annual incomes which are normally distributed with a mean of $32,500 and a standard deviation of $5,000, then determine the percentile rank of a family with an income of 35,000

6            The length of time a person spends in the hospital is approximately normally distributed. A random sample of 20 patients in one hospital had a mean length of stay of 4.2 days with a sample standard deviation of 1.2 days.  Construct a 95% confidence interval for the mean length of stay for all hospital patients.

7          The length of time a person spends in the hospital is approximately normally distributed. A random sample of 20 patients in one hospital had a mean length of stay of 4.2 days with a sample standard deviation of 1.2 days.  Construct a 99% confidence interval for the mean length of stay for all hospital patients.

9          A survey from 200 students was conducted to determine the number of cell phone minutes the average college student uses in a month. The data collected was found to be approximately normally distributed with mean µ = 350, and standard deviation, σ = 30 . Determine the number of students using more than 375 minutes.

Answer 1