1.1. The grades on a math exam for a sample of 40 students are as follows:
52, 98, 71, 63, 80, 55, 92, 67, 85, 74, 59, 96, 61, 83, 76, 53, 99, 68, 81, 72, 57, 94, 60,
88, 79, 51, 97, 64, 82, 75, 58, 91, 65, 86, 78, 54, 90, 69, 84, 70
a. Construct a stem-and-leaf display for these data.
b. Construct a frequency distribution and relative frequency distribution for these data, using
seven class intervals with first class starting from 30.
c. Construct a relative frequency histogram for these data.
d. Describe briefly what the histogram and the stem-and-leaf display tell you about the data.
1.2. The amount of time (in seconds) needed to complete a critical task on an assembly line
was measured for a sample of 50 assemblies. These data are listed here. Draw a histogram to
describe these data.
23.8, 33.1, 34.0, 29.6, 36.4, 34.1, 27.6, 29.1, 26.7, 36.1, 30.9, 32.3, 34.9, 37.3, 37.3,
23.7, 22.7, 26.1, 22.2, 24.1, 20.0, 28.7, 27.9, 25.3, 25.9, 29.0, 26.4, 34.1, 35.9, 32.2,
37.3, 34.3, 30.6, 27.4, 36.2, 24.2, 28.0, 36.7, 24.0, 33.2, 22.6, 29.0, 21.7, 22.3, 29.1,
35.9, 33.8, 24.5, 20.7, 37.5
1.3. Refer to the data: “grades on calculus exam” given in Exercise 1. a. What is the mean
grade of these 40 students? b. What is the variance of the grade? c. What is the standard
deviation of the grade? d. What do the mean and standard deviation of the grade tell you?