Week 6
Assignment: Estimating Sample Size for a Population Proportion
Calculate the sample
size required to estimate a population proportion with a given confidence level
Question
Suppose a clothing store wants to determine
the current percentage of customers who are over the age of forty. How many
customers should the company survey in order to be92% confident that the estimated (sample)
proportion is within5 percentage
points of the true population proportion of customers who are over the age of forty?
|
z0.16 |
z0.08 |
z0.04 |
z0.02 |
z0.01 |
|
0.994 |
1.405 |
1.751 |
2.054 |
2.326 |
Use the table of values above.
Yes that’s right. Keep it up!
307
91
198
77
614
Calculate the sample size required to estimate a population
proportion with a given confidence level
Question
Suppose an automotive repair company wants to determine the
current percentage of customers who keep up with regular vehicle maintenance.
How many customers should the company survey in order to be 90% confident
that the estimated (sample) proportion is within 2 percentage
points of the true population proportion of customers who keep up with regular
vehicle maintenance?
|
z0.10 |
z0.05 |
z0.025 |
z0.01 |
z0.005 |
|
1.282 |
1.645 |
1.960 |
2.326 |
2.576 |
Use the table of values above.
423
609
1,028
1,692
3,383
Calculate the sample size required to estimate a population
proportion with a given confidence level
Question
Suppose
an automotive repair company wants to determine the current percentage of
customers who keep up with regular vehicle maintenance. How many customers
should the company survey in order to be 95% confident that
the estimated (sample) proportion is within 2 percentage
points of the true population proportion of customers who keep up with regular
vehicle maintenance?
|
z0.10 |
z0.05 |
z0.025 |
z0.01 |
z0.005 |
|
1.282 |
1.645 |
1.960 |
2.326 |
2.576 |
Use the table of values above.
322
601
1,692
2,401
9,604
Calculate the sample size required to estimate a population
proportion with a given confidence level
Question
Virginia
wants to estimate the percentage of students who live more than three miles
from the school. She wants to create a 95% confidence
interval which has an error bound of at most 5%. How many students
should be polled to create the confidence interval?
|
z0.10 |
z0.05 |
z0.025 |
z0.01 |
z0.005 |
|
1.282 |
1.645 |
1.960 |
2.326 |
2.576 |
Use the table of values above.
52
73
97
271
385
