Random Sampling and Making Inferences

Customers in two randomly selected groups at a yogurt shop are asked their preference of yogurt flavors. The responses for the customers in each group are summarized in the table above. Based on the information shown in the table, which statement best describes the preferences of the customers in the two groups?

• In both groups, more customers prefer peach-flavored yogurt than either of the other two flavors.

• In both groups, fewer customers prefer vanilla-flavored yogurt than either of the other two flavors.

• In group 2, the same number of customers prefer strawberry-flavored yogurt and vanilla-flavored yogurt.

• In group 1, more customers prefer either strawberry-flavored yogurt or vanilla-flavored yogurt than peach-flavored yogurt.

Which statement best describes a random sample of all students in a middle school?

• Of all the students who are on the track team, the first three to finish a race are selected.

• Of all the students who are in the drama club, every third student on the roster is selected.

• Of all the students who complete an assignment, the first, third, and tenth students are selected.

• Of all the students who attend a school-wide assembly, those sitting in every third seat are selected.

Susan polled 587 people throughout each city in her county.  Each city is the same size.  Is this sample of the residents of cities in the county likely to be biased?

• yes

• no

For a class assignment, Tyler will conduct a survey to find out what students like to do after school. He asks the first 10 people he sees in the gymnasium before school what they like to do after school. Which statement correctly explains whether Tyler's sample is a random sample?

• Tyler’s sample is not random because he only asks 10 people

• Tyler’s sample is not random because he asks people in a gymnasium.

• Tyler’s sample is random because he asks the first 10 people he sees.

• Tyler’s sample is random because he asks each person the same question

Lee will conduct a survey at his school. He will select a random sample of students at the school to take the survey. Which sample is the best random sample for Lee to use?

• every other student in the drama club

• every fifth student who enters the school

• every student who rides the same bus as Lee

• every fourth student in Lee’s homeroom class

Patrick polled the first 27 people to attend the WMS band concert.  Is this sample of the concert attendees likely to be representative?

• yes

• no

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?

• 30 of her friends

• 30 randomly selected students in the school

• 30 students who are often tardy

• 30 students who are often on time

A school principal wants to see which subject the 695 students in his school liked best. Which choice BEST represents a representative sample?

• All girls in the school

• All students who have an A in Social Studies

• All students who are failing science

• 1 class from each grade level