Question

a. Assume that a sample is used to estimate a population mean μ . Find the 80% confidence interval for a sample of size 1101 with a mean of 54.3 and a standard deviation of 20.4. Enter your answer as a tri-linear inequality accurate to 3 decimal places.

b. You want to obtain a sample to estimate a population proportion. Based on previous evidence, you believe the population proportion is approximately p = 0.39. You would like to be 98% confident that your esimate is within 4% of the true population proportion. 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=69.7 . You would like to be 99% confident that
your estimate is within 10 of the true population mean. How large
of a sample size is required?

Answer #1

a)

df = n - 1 = 1101 - 1 = 1100

t critical value at 0.20 significance level with 1100 df = 1.282

80% confidence interval for is

- t * S / sqrt(n) < < + t * S / sqrt(n)

54.3 - 1.282 * 20.4 / sqrt(1101) < < 54.3 + 1.282 * 20.4 / sqrt(1101)

**53.51 <
< 55.09**

b)

Sample size = Z2/2 * p ( 1 - p) / E2

= 2.32632 * 0.39 ( 1 - 0.39) / 0.042

= 804.6

**Sample size = 805** (Rounded up to nearest
integer)

c)

Sample size = (Z/2 * / E)2

= ( 2.5758 * 69.7 / 10)2

= 322.32

**Sample size = 323** (Rounded up to nearest
integer)

You want to obtain a sample to estimate a population
proportion. Based on previous evidence, you believe the population
proportion is approximately p?=11%. You would like to be 99.9%
confident that your esimate is within 5% of the true population
proportion. How large of a sample size is required?

You want to obtain a sample to estimate a population proportion.
Based on previous evidence, you believe the population proportion
is approximately p = 0.14. You would like to be 99% confident that
your esimate is within 2.5% of the true population proportion. How
large of a sample size is required?

You want to obtain a sample to estimate a population proportion.
Based on previous evidence, you believe the population proportion
is approximately p = 19%. You would like to be 95% confident that
your esimate is within 5% of the true population proportion. 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=72.7. You would like to be 99% confident that
your esimate is within 3 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=77.3. You would like to be 99% confident that
your esimate is within 1 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 proportion.
Based on previous evidence, you believe the population proportion
is approximately p∗=87%. You would like to be 99.9% confident that
your esimate is within 3% of the true population proportion. How
large of a sample size is required?
n =

You want to obtain a sample to estimate a population proportion.
Based on previous evidence, you believe the population proportion
is approximately p∗=32%. You would like to be 99% confident that
your esimate is within 4% of the true population proportion. How
large of a sample size is required?
n =

You want to obtain a sample to estimate a population proportion.
Based on previous evidence, you believe the population proportion
is approximately p = 0.33. You would like to be 95% confident that
your esimate is within 2.5% of the true population proportion. How
large of a sample size is required?
n =

You want to obtain a sample to estimate a population proportion.
Based on previous evidence, you believe the population proportion
is approximately p ∗ = 12 % p∗=12% . You would like to be 99.5%
confident that your esimate is within 2% of the true population
proportion. How large of a sample size is required?

ADVERTISEMENT

Get Answers For Free

Most questions answered within 1 hours.

ADVERTISEMENT

asked 8 minutes ago

asked 16 minutes ago

asked 22 minutes ago

asked 27 minutes ago

asked 48 minutes ago

asked 55 minutes ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago