Math 7 CFA 7 Review

Roger compares the goals scored per game by Team A and Team B. What do the box plots tell you about how the goals scored compare for each team? Explain.

• Team A generally scores more goals than team B because the median for Team A is greater than the median for Team B.

• Team B generally scores more goals than Team A because the median for Team B is greater than the median for Team A.

• Both teams score about the same number of goals because the Interquartile Range (IQR) is 3 for both teams.

• Team A generally scores more goals than Team A because their maximum is greater than Team B.

Answer explanation

Team B generally scores more goals than Team A because the median for Team B is greater than the median for Team A.

Roger compares the goals scored per game by Team A and Team B. What do the box plots tell you about the variability of the data? (Hint: look at the length of the rectangle)

• The data for Team A has greater variability than the data for Team B because Team A's maximum is higher than Team B's maximum.

• The data for Team B may have greater variability than the data for Team B because Team B's range is greater than Team A even though their IQR is the same.

• The data for Team A and Team B have about the same variability because they both have the same IQR and the same range.

• The data for Team A has greater variability because there is a greater range between the maximum and the minimum for Team A than for Team B.

Answer explanation

The data for Team B may have greater variability than the data for Team A because Team B's range is greater than Team A even though their IQR is the same.

Belinda randomly surveys students at her school and learns that 7 of 35 respondents own a video gaming system. Based on these data, how many of the 275 students in Belinda's school would be expected to own a video gaming system?

• 15 students

• 25 students

• 30 students

• 55 students

Answer explanation

Based on the survey results, the proportion of students owning a video gaming system is 7/35. Extrapolating to 275 students, the expected number would be (7/35) * 275 = 55 students.

The student council is conducting a survey about the theme for their high school's next dance. Which of the following groups would provide a representative sample of the schools.

• Members of the student council

• Two students chosen randomly from each first hour advisory class.

• Every tenth student to arrive at school

• Students from the school's sports teams

• Students in the student council president's math class.

Answer explanation

The two correct choices are: Two students chosen randomly from each first hour advisory class and Every tenth student to arrive at school. These options provide a representative sample of the school's population because they are random and systematic ways of choosing the sample.

Paisley randomly surveys teachers about the type of car they drive. If Paisley randomly surveys another 200 teachers, estimate how many would she expect to drive an SUV?

• 63

• 94

• 102

• 125

Answer explanation

Based on the initial survey, 31.5% of teachers drove an SUV. Therefore, out of the next 200 teachers, we can expect approximately 63 to drive an SUV (31.5% of 200).

Braden is comparing statistics about the prices of DVD players from two different stores. Compare the measures of center of the data sets. Select ALL correct statements.

• DVD players cost less, on average, at Store A.

• DVD players cost less, on average, at Store B.

• The data for Store B have a greater mean and a greater median than Store A.

• The data for Store A have a greater mean, but not a greater median, than Store B.

• The range for Store A is greater than the range for Store B.

Answer explanation

The correct statements are that DVD players cost less, on average, at Store B and that the range for Store A is greater than the range for Store B.

Braden is comparing statistics about the prices of DVD players from two different stores. Compare the variability of the data of each store. Select ALL correct statements.

• The range and IQR are greater at Store B as compared to Store A.

• The range and IQR are greater at Store A as compared to Store B.

• There is more variability, or spread, in prices of DVD players at Store A.

• There is more variability, or spread, in prices of DVD players at Store B.

Answer explanation

The range and IQR are greater at Store A as compared to Store B. There is more variability, or spread, in prices of DVD players at Store A.

Walmart buys lemons from two different companies. The mean weight of Company A's lemons is 4.5 oz. The mean weight of Company B's lemons is 4.2 oz. The MAD of both data sets is 1. What can you infer about the two sets of oranges?

• The MAD is large.

• The data sets are very different.

• The variabilities of the sets of lemons are similar.

• The mean is small.

Answer explanation

The variabilities of the sets of lemons are similar.

Data from a random survey asking sixth and seventh graders about the number of siblings in their families are recorded in the dot plots below. Compare the mean values of the data sets.

• Students in sixth grade have 5 more siblings.

• Students in seventh grade have fewer siblings.

• Students in each grade have a similar number of siblings.

• There is no difference in the number of siblings by grade.

Answer explanation

Students in each grade have a similar number of siblings because the mean values of the data sets are comparable.

Riley records the number of homework assignments completed by randomly selected students in her school on Monday in the table below.

Grade 8: 5, 4, 5, 4, 4, 5, 4, 5

Grade 7: 6, 5, 5, 5, 6, 6, 5, 6

Grade 6: 5, 3, 4, 3, 5, 4, 4, 4

Make a comparative inference based on the mean.

Put the grades in order from the least to the greatest mean number of assignments.

• Grade 6

• Grade 8

• Grade 7