Samples Populations Bias Inferences

_______ is the entire group of objects or individuals considered for a survey.

• Sample

• Quartile

• Random Sample

• Population

_______ is a part of a group being surveyed.

• Sample

• Population

• Quartile

• Random Sample

You want to know how many students catch the bus to go home.  You go to the bus stop and ask students how they go home from school.  Is this a random sample or biased sample?

• BIASED

• RANDOM

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

• The girls in the school.

• 1 classroom for each grade

• All the students in the school.

• The students making a B in math.

In a certain school, students can choose whether to eat in the school’s cafeteria. A reporter working for the school’s newspaper polled students on their reactions to changes in the menu at the cafeteria. For each student leaving the cafeteria in one 20-minute time period, the reporter used a die to determine whether to stop the student and ask how he or she felt about the new menu. In the reporter’s article it was stated that a random sample of the students showed that 23% of the school’s student population was happy with the new menu. Which of the following statements is true?

• Because each student leaving the cafeteria was randomly selected and could choose to answer or not, this is a random sample of the student population, and the 23% is an accurate measurement of the school population’s view of the new menu.

• Because students self-selected whether to eat in the cafeteria, the sampling method might be biased and the sample might not be representative of all students in the school.

• The survey would have been more effective if the reporter had collected the data in one 10-minute time period rather than in one 20-minute time period.

• The survey would have been more effective if students who cared about the food could have called the reporter to tell how they felt about the new menu, so that only students with opinions on the subject would have been surveyed.

• Because no treatment was imposed on the students eating in the cafeteria, one cannot make any conclusions about the new menu.

Tanya wants to know the percent of people likely to attend the upcoming musical at school. She asks each person in the musical how many people they know who are coming to make a prediction. Why is this sample biased?

• Drama students are more likely to lie.

• Musicals are better attended than plays.

• The drama teacher was not asked.

• The sample is not random and not representative of the entire school population.

Answer explanation

The sample is not random and not representative of the entire school population, as it only includes people involved in the musical, leading to bias.

As part of a 7th grade statistics project, the teacher brings a candy jar full of gumballs (red & green). The assignment is to estimate the proportion of red gumballs in the jar. Suppose one of the students draws 25 gumballs from the jar: 8 are red, 17 are green. What is the SAMPLE?

• 25 gumballs drawn

• all gumballs in the jar

• the students

• the 17 green gumballs

The counselors at a camp are scheduling activities for family visitation day. They decide to conduct a survey to determine which activities campers would most like to share with their families. Which describes a method for getting a sample that is both representative and random?

• During the dinner hour, announce that any camper interested in doing so can collect and complete a survey.

• During camp free time, ask every fifth camper in the arts and crafts hall to complete a survey.

• During morning roll call, ask every tenth camper to complete a survey.

• During camp free time, ask all campers down at the lake to complete a survey.

• 14 7th graders

• 28 7th graders

• 35 7th graders

• 42 7th graders

River Bluff High School has a student population of 3020. In a sample of 250 students, 170 of them were female athletes. Approximately how many students in the entire population should be female athletes?

• 170

• 205

• 2,054

• 2,770