Question

1.)

You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is σ=49.3σ=49.3. You would like to be 99% confident that you estimate is within 5 of the true population mean.

How large of a sample size is required?

*n* =

Note: Use z-scores rounded to 3 decimal places in your calculations.

2.)

You want to obtain a sample to estimate a population mean. Based
on previous evidence, you believe the population standard deviation
is approximately σ=26.1σ=26.1. You would like to be 99% confident
that you estimate is within 3 of the true population mean. How
large of a sample size is required?

*n* =

Note: Use z-scores rounded to 3 decimal places.

3.)

**Internet and Mobile Devices.** In a 2012 survey
of approximately 2275 American adults, 387 of them do their
browsing on their phone rather than a computer or other
device.

(a) Calculate a 98% confidence interval for the proportion of
Americans who access the internet on their cell phones, and
interpret the interval in this context.

( , )

(b) Interpret the confidence interval in the context of the
study:

- We can be 98% confident that the proportion of Americans who use their cell phones to access the internet is in this confidence interval
- 98% of Americans use their cell phone to access the internet
- We can be 98% confident that our confidence interval contains the sample proportion of Americans who use their cell phones to access the internet

Answer #1

1)

Solution :

Given that,

Population standard deviation = = 49.3

Margin of error = E = 5

At 99% confidence level the z is ,

= 1 - 99% = 1 - 0.99 = 0.01

/ 2 = 0.01 / 2 = 0.005

Z_{/2}
= Z_{0.005} = 2.576

sample size = n = (Z_{/2}*
/ E) ^{2}

n = (2.576 * 49. 3/ 5)^{2}

n = 645.12

n = 646

Sample size = 646

You want to obtain a sample to estimate a population mean. Based
on previous evidence, you believe the population standard deviation
is approximately σ=35.3σ=35.3. You would like to be 95% confident
that your estimate is within 0.1 of the true population mean. How
large of a sample size is required?
As in the reading, in your calculations:
--Use z = 1.645 for a 90% confidence interval
--Use z = 2 for a 95% confidence interval
--Use z = 2.576 for...

You want to obtain a sample to estimate a population mean. Based
on previous evidence, you believe the population standard deviation
is approximately σ=59.1σ=59.1. You would like to be 90% confident
that your estimate is within 5 of the true population mean. How
large of a sample size is required?
As in the reading, in your calculations:
--Use z = 1.645 for a 90% confidence interval
--Use z = 2 for a 95% confidence interval
--Use z = 2.576 for...

You want to obtain a sample to estimate a population mean. Based
on previous evidence, you believe the population standard deviation
is approximately σ = 36.9 . You would like to be 98% confident that
your estimate is within 0.2 of the true population mean. How large
of a sample size is required?

You want to obtain a sample to estimate a population mean. Based
on previous evidence, you believe the population standard deviation
is approximately σ=43.8σ=43.8. You would like to be 98% confident
that your estimate is within 5 of the true population mean. How
large of a sample size is required?

You want to obtain a sample to estimate a population mean. Based
on previous evidence, you believe the population standard deviation
is approximately σ=59.2. You would like to be 98% confident that
your estimate is within 10 of the true population mean. How large
of a sample size is required?
n = __________________

You want to obtain a sample to estimate a population mean. Based
on previous evidence, you believe the population standard deviation
is approximately σ = 63.5 . You would like to be 98% confident that
your estimate is within 4 of the true population mean. How large of
a sample size is required? n = ?

You want to obtain a sample to estimate a population mean. Based
on previous evidence, you believe the population standard deviation
is approximately σ = 56.5 . You would like to be 98% confident that
your esimate is within 4 of the true population mean. How large of
a sample size is required?
n =

You want to obtain a sample to estimate a population mean. Based
on previous evidence, you believe the population standard deviation
is approximately σ = 44.3 . You would like to be 98% confident that
your estimate is within 1.5 of the true population mean. How large
of a sample size is required?
n =_______
Do not round mid-calculation. However, use a critical value
accurate to three decimal places — this is important for the system
to be able to...

You want to obtain a sample to estimate a population mean. Based
on previous evidence, you believe the population standard deviation
is approximately σ=56.5. You would like to be 98% confident that
your esimate is within 4 of the true population mean. How large of
a sample size is required?
Do not round mid-calculation. However, use a critical value
accurate to three decimal places — this is important for the system
to be able to give hints for incorrect answers....

You want to obtain a sample to estimate a population mean. Based
on previous evidence, you believe the population standard deviation
is approximately σ = 45.1 σ = 45.1 . You would like to be 95%
confident that your estimate is within 10 of the true population
mean.
How large of a sample size is required?

ADVERTISEMENT

Get Answers For Free

Most questions answered within 1 hours.

ADVERTISEMENT

asked 2 minutes ago

asked 8 minutes ago

asked 47 minutes ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 2 hours ago

asked 3 hours ago

asked 3 hours ago

asked 3 hours ago

asked 4 hours ago

asked 4 hours ago