MATH 3070: Worksheet No.2
NAME:
1. Report your findings regarding Exercise 3.42/3.43. (Data file ex3-42.csv)
(a) Give a short description of the data and the variable(s) in the data file.
(b) Calculate the standard deviation of the treatment times.
(c) Find the 25th percentile for the treatment times and interpret this value. The health clinic
advertises that 90% of all its patients have a treatment time of 40 minutes or less. Do the
data support this claim?
(d) Construct a boxplot for the data.
2. Report your findings regarding Exercise 3.44. (Data file ex3-44.csv)
(a) Give a short description of the data and the variable(s) in the data file.
(b) Construct a relative frequency histogram to describe these data.
(c) Calculate the sample means y, and the sample standard deviation s.
(d) Construct the intervals (y-s, y+s), (y-2s, y+2s), and (y-3s, y+3s). Count the percentages of
squares falling in each of the three intervals, and compare these percentages with the
corresponding percentages given by the Empirical Rule.
3. Report your findings regarding Exercise 3.46. (Data file ex3-46.csv)
(a) Give a short description of the data and the variable(s) in the data file.
(b) Compute the mean and standard deviation for the room rates for both luxury and budget
hotels.
(c) Calculate the coefficient of variation (CV) for each type of hotel. Argue that luxury hotels
have a more variable room rate than budget hotels.
(d) Give a practical reason why the luxury hotels are more variable than the budget hotels.
4. Report your findings regarding Exercise 3.55. (Data file ex3-55.csv)
(a) Give a short description of the data and the variable(s) in the data file.
(b) Compute the mean and standard deviation for the deviations of each supplier.
(c) Construct boxplot(s) for the data.
(d) Describe the deviation from specified strength for the three suppliers.
(e) Which supplier appears to provide material that produces lenses having strength closest to
the target value?
5. Report your findings regarding Exercise 3.58. (Data file ex3-58.csv)
(a) Give a short description of the data and the variable(s) in the data file.
(b) Construct a relative frequency histogram for the data.
(c) Calculate the mean y and median of the successful demands between failures.
(d) Which measure appears to best represent the center of the data?
(e) Calculate the interquartile range and standard deviation s.
(f) Construct the intervals (y-s, y+s), (y-2s, y+2s), and (y-3s, y+3s). Count the number of
demands between failures falling in each of the three intervals. Convert these numbers to
percentages and compare your results to the Empirical Rule. Discuss why the Empirical
Rule and the actual percentages do not match well?