Inference and Population

A sample should be

• representative of only middle school students

• a very large group

• representative of the population

• representative of people who volunteer

Lucy collects data from a random sample of seventh-graders. Out of 40 respondents, 7 attend after-school programs. Of the 200 seventh-graders attending Lucy’s school, how many would be expected to attend afterschool programs?

Margo wants to convince her father to change her curfew from 9 P.M. to 10 P.M. She gathers data on curfew times from a random sample of students at her middle school. Can Margo use these data to present a valid inference that will convince her father? Explain.

• Yes; Most students have a curfew of 10 P.M. or later.

• Yes; More students have a curfew of 9 P.M. than any other time.

• No; Most students have a curfew of 9 P.M. or earlier.

• No; More students have a curfew of 10 P.M. or 11 P.M. than 8 P.M.

Group A and Group B were randomly sampled from the same population. Select all the inferences that you can make.

• Group B has a higher median than Group A.

• Group B has a higher mean than Group A.

• Group B has more overall variability than Group A.

• Group B has a smaller range than Group A.

• Group A and B have the same maximum value.

The table shows the results of a survey of 200 people attending a hockey game.
The attendance for the hockey game is about 25,000 visitors each game.  Based on the table, how many people out of 25,000 could be expected to buy a pennant?

• 1,375

• 1,650

• 2,750

• 3,850

True or False: all samples lead to a good prediction about an entire population.

• True

• False

Caleb is comparing the growth of plants using two different fertilizers. Use the measures of center from the box plots to make an inference about the data.

• Based on the means, plants in Group A grew more than plants in Group B

• Based on the means, plants in Group B grew more than plants in Group A.

• Based on the medians, plants in Group A grew more than plants in Group B

• Based on the medians, plants in Group B grew more than plants in Group A.

The dot plot shows a random sample of the number of fish caught and released by 30 participants during a two-day fishing derby. Use the mean value of each data set to make an inference about the number of fish caught each day.

• On average, most participants caught and released 5 or more fish.

• More participants caught 6 fish than any other number.

• The same participants who caught and released 1 fish the first day caught and released 1 fish the second day.

• On average, participants caught and released more fish on Day 2.

There are 400 students at Polly's school. She surveyed a random sample of 80 students to find their favorite hobby. 19 said they like to read. 30 said they like to be with friends. 8 said they like to do crafts. 23 said they like to play sports. Polly infers that doing crafts is the least popular hobby at her school. Refer to the data table. Polly surveys two more samples. Do the results from these samples support the inference made from the first sample?

• Yes, the survey results support the inference that doing crafts is the least popular hobby at Polly's school.

• No, the survey results does not support the inference that doing crafts is the least popular hobby at Polly's school.

The two data sets show the number of days that team members trained before a 5k race. What inference can you draw by comparing the median?

• There is more variability in the number of days that Team A members trained because the IQR for Team A is greater than the IQR for Team B.

• There is more variability in the number of days that Team B members trained because the IQR for Team B is greater than the IQR for Team A.

• Team A members generally trained for more days than Team B members

• Team B members generally trained for more days than Team A members