Q. A sample of 160 workers in the downtown area classified each worker by race. A bar graph of the results is given below, but the bar for black workers in the graph below has been omitted.
Using the information provided, the proportion of black workers in the sample must be
A. 40% B. 25% C. 20%
Q. A sample was taken of the salaries of four employees from a large company. The following are their salaries (in thousands of dollars) for this year.
33 31 24 36
The variance of their salaries is
A. 5.1 B. 26 C. 31
Q. In a class of 25 students, 22 students had grades between 71 and 80 (both endpoints included), and three students had grades between 91 and 100 (both endpoints included). For these data,
A. the median must be between 71 and 80.
B. the mean must be between 71 and 80.
C. both answers are correct.
Q. The scores on the Survey of Study Habits and Attitudes (SSHA) for a sample of 150 first-year college women produced the following boxplot and descriptive statistics using MINITAB.
The number of women with scores between 93.26 and 129.23 is
A. about 75. B. about 50. C. about 36.
Q. The time for students to complete a standardized placement exam given to college freshman has a normal distribution with a mean of 62 minutes and a standard deviation of 8 minutes. If students are given one hour to complete the exam, the proportion of students who will complete the exam is about
A. 0.25. B. 0.40. C. 0.60.