Algebra2 Name

7.2worksheetDateHour

1. Suppose a student wants to estimate the average number of minutes that FHN students spend on social media each week. Why is it better for the student to randomly choose students from throughout the school by using randomly generated student numbers, rather than just asking students that he or she has classes with?

2. Here are two studies.

First study: Ann Landers, an advice columnist who used to write a column that ran in newspapers across the country, asked her readers who are parents, “If you had to do it over again, would you have children?” About 70% of more than 10,000 people wrote to her and said that no, having kids was not worth it. / Second study: A randomly selected survey conducted at a later date showed that about 90% of parents are happy with their decision to have children and, if they were to do it all over again, would make the same choice to have children.

What accounts for the difference in these two results?

Which study can be used to make an inference about the population consisting of all parents? Why?

3. Which of these is/are random samples? Explain why or why not.

To estimate the percent of FHN students who wake up before 6am for school, a student…

a. asked 12students in his first hour class if they get up before 6am for school.

b. prepared index cards with all the days of the year written on them (one date per card) and then, during an assembly, was allowed to select 8 birthdays from the shuffled deck of index cards so he could ask all those students with that particular birthday if they get up before 6am for school.

c. asked all the students who attended the homecoming dance if they get up before 6am for school.

d. created a spinner with 2 spaces on it, one labeled, “Do you get up before 6am for school?” and the other labeled, “I don’t have any questions for you, but I hope you have a good day.” He was allowed to have each student, over the course of the year, be called down to the office to spin the wheel and answer the question, if the spinner landed on it.

e. was allowed to put a stack of surveys on a table in the commons at lunch, inviting students to answer the question, “Do you get up before 6am for school?”

f. asked his best friends if they get up before 6am for school.

4. Even more of these! Which of these is/are random samples? Explain why or why not.

To estimate the percent of FHN students who wake up before 6am for school, a student…

a. asked each person at his lunch table if they get up before 6am.

b. gave the guidance office a list of 400 6-digit numbers that he came up with, off the top of his head. The counselors identified students that had ID numbers that matched those student-generated numbers and the student then asked those students if they get up before 6am for school.

c. gave the guidance office a list of 400 6-digit numbers that a computer created. The counselors identified students that had ID numbers that matched those computer-generated numbers and the student then asked those students if they get up before 6am for school.

d. went to the St. Peters Rec-Plex at 5am to look or FHN students who might be there getting in a morning workout, swim practice, or ice practice and asked each FHN student there if they get up before 6am.

5. Suppose that a health inspector is visiting a doggie day care facility and is going to randomly examine the health and activity level of 4 of the 22 dogs that are there today.

a. Describe a statistically appropriate procedure for randomly selecting 4 dogs. Include enough detail that a student in another class could carry out your procedure.

b. Describe a procedure for selecting 4 dogs that is not a random sampling method and identify what statistical problem could arise if you use that improper method.

6. A chair manufacturer is going to inspect 3 of the 9 hand-carved chairs made this week. The chairs have been numbered with single-digit numbers 1-9. Use this line of a random number table to choose the 3 chairs that will be inspected.

95592 94007 69971

7. One particular hallway of a school has 30 classrooms and 4 of them will be randomly selected to have the air quality tested. The rooms already have room numbers 10-39, so we’ll use those 2-digit labels. Use this line of a random number table to choose the 4 rooms that will be inspected.

19365 15412 39638 85453 46816 83485