Inferences from Samples about Populations

A student wants to know which type of pizza the students at his middle school prefer. Which option would give a unbiased, representative sample:

• Asking all the students in the hot lunch line.

• Asking 10 random students from each homeroom.

• Asking every other student who gets off a school bus.

• Asking all the 8th graders.

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

Mrs. Seats is conducting a survey to find out the favorite snack of sixth and seventh graders. She will ask a sample of 100 students. Which of the groups below should be surveyed to get the BEST representative sample?

• 100 students at the movie theater

• the first 100 students who go to a local baseball game

• 5 students from each of the 20 local middle schools

• 20 random students from each of the 5 local sixth- and seventh-grade schools

• 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

Several students were surveyed about their favorite drinks. 22 said orange soda, 34 Pepsi, 40 coke, and 29 grape soda. Predict how many students will like coke if 500 students are surveyed?

• 12.5

• 40

• 160

• 167

Mrs. Debenport surveyed 8 random band members and found that 3 members play more than one instrument. Use her results to predict how many of Meadow Glen's 152 band members play more than one instrument.

• 3/8

• 57

• 95

• 405

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 students who are often tardy

• thirty students who are rarely tardy

• thirty of her friends

• thirty randomly selected students from her school

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.

Litzy collects data from a random sample of 7th graders. Out of 40 respondents, 7 attend afterschool programs. Of the 200 7th graders attending Litzy's school, how many would be expected to attend afterschool programs?

• 14 7th graders

• 28 7th graders

• 35 7th graders

• 42 7th graders