Inferences Random Samples

Assign each car in a dealership a number and then use a random-number table to select the cars to be inspected. 

• systematic

• random sample

• convenience

• biased sampling

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?

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.

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.

Students in Mrs. Walsh’s math class wanted to know the favorite snacks of students in the school. How could they generate a random sample to survey?

• Line up the students by height and choose the first 20 students

• Use the school roster and randomly choose 50 boys.

• Obtain an alphabetized list of all the students in the school and select every seventh student

• Place all the names of the students in Mrs. Walsh's math class in a hat and randomly select 10 students.

Russell randomly surveys seventh-graders in his school and finds that 6 of 30 attend summer camp. If there are 200 seventh-graders in his school, about how many are expected to attend summer camp? Enter your answer in the box.

_________ is a sample in which each individual or object in the entire population has an equal chance of being selected.

• Sample

• Population

• Random Sample

• Quartile

A sample in which every person, object, or event has an equal chance of being selected.

• Random sample.

• Biased sample.

Ana wants to know the average student’s opinion of the tardy policy at her school. Which group of students should she survey in order to achieve the most accurate results?

• Thirty randomly selected students from her school

• Thirty students who are rarely tardy

• thirty of her friends