Comparative Inferences About Population

The following box plots show the frequency of test scores on a recent math test in two classes. Make a comparative inference about the populations based on the IQR. Choose the correct answer below. ?

• Class 1 has more varied class scores.

• Class 2 has more varied class scores.

• Class 1 has more consistent class scores.

• Both classes have equality consistent scores.

The following box plots display how fast two different types of animals can run. Compare the median of each box plot.

• The medians are about the same.

• Animal 1 has a greater median.

• Animal 2 has a greater median.

In an effort to try to convince her mother that she is too old to join the intermediate swim​ class, Mira, who is 13 years​ old, gathers data on the ages of a random sample of members of the current intermediate swim class. The results of the data collected by Mira are displayed in the dot plot shown.

• It is likely that she will be able to convince her mother.​ Mira's age is within the area where the data are clustered.

• It is likely that she will be able to convince her mother.​ Mira's age is to the left of the area where the data are clustered.

• It is unlikely that she will be able to convince her mother.​ Mira's age is within the area where the data are clustered.

• It is unlikely that she will be able to convince her mother.​ Mira's age is to the left of the area where the data are clustered.

There are two movie theaters in a town. A student wants to compare the amount of money each theater makes over a period of days. The following box plots show the data for the amount of money each theater makes over a period of days. Compare the median of each box plot.

• The medians are about the same.

• Theater 1 has a greater median.

• Theater 2 has a greater median.

The table shows the finish times of 30 runners in the 100-meter dash. Which inference is true?

• The runners ran faster this year, on average, as compared to last year.

• Most runners ran faster last year, on average, as compared to this year.

• Every runner ran faster this year as compared to last year.

The table shows the finish times of 30 runners in the 100-meter dash. Which inference is true?

• The runners ran faster this year, on average, as compared to last year.

• Most runners ran faster last year, on average, as compared to this year.

• Every runner ran faster this year as compared to last year.

In a random sample of 20 students from a class, 8 students said they participate in after-school sports. Predict the total number of students participating in after-school sports in a school of 400 students.

• 160

• 80

• 120

• 200

Answer explanation

To find the total number of students participating in after-school sports in a school of 400 students, we can use the ratio method. 8 students out of 20 participate, so 8/20 = x/400. Solving for x gives us 160 students.

How can sample data be used to form an estimate about the population?

• A proportion can be solved to relate the sample to the population.

• A proportion can be solved to relate the sample to the mean.

• A proportion can be solved to relate the sample to the median.

• You cannot make an estimation from sample data.

A random sample of 80 books at a library showed that 32 books were fiction. Predict the total number of fiction books in a library that has 400 books.

• 160

• 200

• 140

• 120

Answer explanation

To find the total number of fiction books in the library, we can set up a proportion: 32 books out of 80 are fiction, so 400 books would have (32/80) * 400 = 160 fiction books.

The box plots show the amount of time farmers from two farms spent harvesting crops over the past 2 months. What inference can be made based on the IQR of both Farms?

• Farm 2 has more variability in hours spent harvesting.

• Farm 1 has more consistent hours spent harvesting.

• Farm 2 has more consistent hours spent harvesting.

• Both farms are equally varied in the hours spent harvesting.