NAME:...................................................................................

ID #:............................................................................

THE EXAM WAS ...........EASY ..........FAIR ..........DIFFICULT

FOR INSTRUCTOR'S USE

1.

2.

3.

4.A

4.B

1. Medical researchers at UCLA administered a new experimental drug for arthritis to 15 subjects. They recorded the following number of minutes elapsed before the drug showed any effect:

77

59

3

70

54

79

67

38

46

66

75

55

60

38

47

a. Make a stemplot of these data and interpret.

b. Compute the mean and the range

c. Give the five-number summary for this distribution.

d. Construct a boxplot and interpret.

e. Use the 1.5xIQR criterion to spot suspected outliers.

f. Based on the shape of this distribution, would you be willing to report the mean and standard deviation as helpful descriptive measures for the number of minutes elapsed before the drug showed any effect? Please justify your answer.

2. Each of the workers in Acme Clothing Company was given an aptitude test to determine suitability for particular jobs. Laura Snyder's results as well as the results of the other workers who took the test are shown in the table.

Skill	Mean Test Score	Standard Deviation	Laura's Score
Marketing/sales	61	7.8	71
Inventory/shipping	42	3.1	46
Personnel	83	5.9	87

Relatively speaking, in which skill does she have the most talent? Please justify your answer

3. Professor Rogers has found that the grades on the nursing final exam are normally distributed with a mean of 64 and a standard deviation of 11.

a. If the passing grade is 54, what proportion of the class will fail?

b. What is the proportion of the class who will score between 54 and 75?

c. What is the proportion of the class who will score more than 85?

d. How low a score must one have in order to be placed in the bottom 10% of the class?

e. How high a score must one have in order to be placed in the top 10% of class?

4.

A. An owner of a health spa wished to study the relationship between the temperature (x) in degrees Fahrenheit at 11 a.m. and the number (y) of customers using the facilities at that time for 6 randomly selected days during the summer.

a. Suppose that the least squares regression line is y=66.3-0.6x. Interpret 66.3 and -0.6.

b. Predict the number of customers using the facilities at 11 a.m. for a day on which the temperature is 65 degrees.

c. On one of the days sampled the temperature was 65 degrees and the number of customers was 27. Find the residual for this day.

d. Given the least squares regression line in part (a), what would be the sign of the correlation coefficient r. Please justify your answer.

4.

B. Interpret the following scatter plots.