7.03 Comparative inferences

The weights, in kilograms, of two groups ofpeople were recorded and presented in a stem-and-leaf plot as shown:

Key: 4 \vert 2 = 42

Isabelle thinks there may be a difference in the way musicians and athletes compute certain puzzles. She gave an equal number of musicians and athletes a knot to undo and recorded how long, in seconds, it took each of them. The results are presented in the table:

• Musicians: \, 32,\, 37,\, 36,\, 37,\, 39,\, 37,\, 35,\, 38,\, 37

• Athletes: \, 36,\, 36,\, 46,\, 37,\, 45,\, 45,\, 28,\, 41,\, 45

One form of neurological testing is to see how well you can do two things at once. Ten people were asked to recount every second letter of the alphabet while walking in a straight line. They were then asked to do the same task while seated and still. The number of mistakes each person made are listed below:

• While walking: \, 7,\, 4,\, 6,\, 4,\, 0,\, 1,\, 5,\, 3,\, 1,\, 4

• While seated: \, 3,\, 4,\, 4,\, 2,\, 0,\, 2,\, 3,\, 2,\, 1,\, 2

The following box plots shows the number of points scored by two basketball teams in each of their matches:

The following histograms show the results of two groups of athletes, Group A and Group B, and the number of games (frequency) in which they scored a certain number of points:

Marge grows two different types of bean plants. She records the number of beans that she picks from each plant for 10 days. Her records are shown below:

• Plant A: 10,\, 4,\, 4,\, 5,\, 7,\, 10,\, 3,\, 3,\, 9,\, 10

• Plant B: 8,\, 7,\, 5,\, 5,\, 9,\, 7,\, 8,\, 7,\, 5,\, 6

The following box plots summarize results from a medical study. The treatment group received an experimental drug to relieve cold symptoms, and the control group received a placebo. The box plots show the number of days each group continued to report symptoms:

The ages of employees at two competing fast food restaurants on a Saturday night are recorded. Some statistics are given in the following table:

The beaks of two groups of bird are measured, in millimeters, to determine whether they might be of the same species. The measurements are shown below:

• Group 1: \,33,\, 39,\, 31,\, 27,\, 22,\, 37,\, 30,\, 24,\, 24,\, 28

• Group 2: \, 29,\, 44,\, 45,\, 34,\, 31,\, 44,\, 44,\, 33,\, 37,\, 34

Isabelle is trying to decide which country to move to. She finds some jobs related to her field in each country, and looks at the advertized salary. The table shows the results:

The following table shows the grades obtained by a student in two subjects:

A scientist examined 10 crickets and 10 katydids one night, and collected data on how many chirps they made per minute. His observations are presented in the following table:

• Crickets: \, 53,\, 48,\, 53,\, 51,\, 51,\, 51,\, 47,\, 53,\, 49,\, 47

• Katydids: 106,\, 106,\, 113,\, 106,\, 112,\, 111,\, 110,\, 109,\, 113,\, 110