Practice B

Name———————————————————————— Lesson
Lesson 6.4
6.4
Date —————————————
Practice B
For use with the lesson “Select and Draw Conclusions from Samples”
Identify the type of sample described. Then tell if the sample is biased.
Explain your reasoning.
1. A consumer advocacy group wants to know if car owners believe their car is reliable.
The group randomly selects 1020 car owners and mails out a survey to each one.
2. A grocery store wants to know which day of the week consumers prefer to do their
grocery shopping. Everyone who shops at the store on Friday is asked which day of
the week they prefer to do their grocery shopping.
3. A survey of students’ favorite school subjects is being conducted. Every other
student in the math club is asked “Which school subject is your favorite?”
Find the margin of error for a survey that has the given sample size.
Round your answer to the nearest tenth of a percent.
4. 200
5. 350
8. 5200
9. 495
6. 1100
10. 280
7. 2600
11. 9000
12. 62%
13. 64%
14. 69.5%
15. 62.7%
16. 64.5%
17. 60.5%
18. 63.6%
19. 67.5%
In Exercises 20 and 21, use the following information.
Technology Survey In a survey of 504 people in the United States, about 11% said that
the influx of new technologies such as computers has left them feeling overwhelmed.
20. What is the margin of error for the survey? Round your answer to the nearest tenth
of a percent.
21. Give an interval that is likely to contain the exact percent of all people in the United
States who feel overwhelmed by the influx of new technologies.
In Exercises 22–25, use the following information.
TV in the Bedroom A survey reported that 510 kids ages 8 to 18, or 68% of those
surveyed, have a TV in their bedroom.
22. How many kids ages 8 to 18 were surveyed?
23. What is the margin of error for the survey? Round your answer to the nearest tenth
of a percent.
24. Give an interval that is likely to contain the exact percent of all kids ages 8 to 18
who have a TV in their bedroom
25. About how many kids ages 8 to 18 should be surveyed to have a margin of error
of 2.5%?
6-42
Algebra 2
Chapter Resource Book
Copyright © Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Find the sample size required to achieve the given margin of error.
Round your answer to the nearest whole number.
Lesson 6.3 Use Normal
Distributions, continued
5. 0.051
Practice Level A
Real-Life Application
Challenge Practice
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2. $50.80 is below the mean, $77.80 is above the
mean, $61.60 is above the mean. 3. a. 75.8%
b. about 505 4. 2.87%; yes, because only 2.87%
of light bulbs have a life span of more than 3085
hours. 5. a. 0.6 b. 22.1 c. A 5 84.1, B 5 78.5,
C 5 71.5, D 5 65.9
Lesson 6.4 Select and Draw
Conclusions from Samples
Teaching Guide
Copyright © Houghton Mifflin Harcourt Publishing Company. All rights reserved.
1. Check student responses.
2. Sample answer: It can change the results to
a more favorable or less favorable majority if the
people surveyed are not randomly chosen. Most
teachers would say “yes.” Most students would
say “no.”
3. Sample answer: The more people surveyed,
the more likely the survey will yield meaningful
results; 100 students in hall; the first sample is
very small, and if they are eating in the cafeteria,
chances are they like the food.
Graphing Calculator Activity
1. Sample answer: Make a list of the 57 employees,
and assign each of these employees a different
number from 1 to 57. Generate 12 unique random
integers from 1 to 57. For each number that is
generated, circle the corresponding employee on
your list. If a number is repeated, simply discard it
and generate a new, unique number. 1, 13, 14, 16, 29,
39, 41, 45, 47, 48, 53, 56 2. Sample answer: Make
a list of the 249 members, and assign each of these
members a different number from 1 to 249. Generate
25 unique random integers from 1 to 249. For each
number that is generated, circle the corresponding
1. systematic; biased; People attending a
baseball game may be likely to say baseball is
their favorite sport. 2. self-selected; unbiased;
People entering a pet store would not be biased
toward any one particular animal.
3. convenience; biased; Members leaving an
aerobics class are more likely to attend aerobics
classes than other members. 4. 66.7%
5. 610.0% 6. 64.0% 7. 61.7% 8. 61.5%
9. 63.6% 10. 65.1% 11. 61.1%
12. 204 people 13. 278 people 14. 156 people
15. 123 people 16. 816 people 17. 2066 people
18. 434 people 19. 3460 people 20. 63.5%
21. between 12.5% and 19.5%
22. Sample answer: Assign each person a
number from 1 to 15,000 and use a random
number generator to generate 800 unique
numbers.
23. Sample answer: Selecting people who
currently have children attending a school in the
school district. 24. Sample answer: Mailing a
survey to each person and then counting the first
800 that are received (self-selected).
answers
1. 2.5% 2. 95% 3. 0.815 4. 0.000625
member on your list. If a number is repeated, simply
discard it and generate a new, unique number. 45,
74, 75, 77, 83, 94, 98, 126, 129, 143, 148, 151, 155,
157, 161, 179, 189, 190, 192, 204, 213, 221, 226,
245, 247
Practice Level B
1. random sample; unbiased; The sample is
representative of the population (car owners).
2. convenience sample; biased; Consumers
shopping on a Friday probably prefer to shop
on that day. 3. systematic; biased; Students in
the math club are more likely to prefer math
than other students.
4. 67.1% 5. 65.3% 6. 63.0% 7. 62.0%
8. 61.4% 9. 64.5% 10. 66.0% 11. 61.1%
12. 2500 13. 625 14. 111 15. 1372 16. 494
17. 40,000 18. 772 19. 178 20. 4.5%
21. between 6.5% and 15.5% 22. 750 23. 3.7%
24. between 64.3% and 71.7% 25. 1600
Algebra 2
Chapter Resource Book
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