Question

for a sample of size n=15

the critical z-score for 82% confidence is _ (two decimal accuracy, positive value only)

the critical t-score for 95% confidence is _ (three- decimal accuracy, positive value only)

Answer #1

solution

At 82% confidence level the z is ,

= 1 - 82% = 1 - 0.82 = 0.18

/ 2 = 0.18 / 2 = 0.09

Z_{/2}
= Z_{0.09} = 1.34

(B)n = 15

Degrees of freedom = df = n - 1 = 15- 1 = 14

At 95% confidence level the t is ,

= 1 - 95% = 1 - 0.95 = 0.05

/ 2 = 0.05 / 2 = 0.025

t_{
/2,df} = t_{0.025,14} =
**2.145 **

Determine the t critical value for a two-sided
confidence interval in each of the following situations. (Round
your answers to three decimal places.)
(a) Confidence level = 95%, df = 5
(b) Confidence level = 95%, df = 15
(c) Confidence level = 99%, df = 15
(d) Confidence level = 99%, n = 10
(e) Confidence level = 98%, df = 21
(f) Confidence level = 99%, n = 34

When σ is unknown and the sample is of size n
≥ 30, there are two methods for computing confidence intervals for
μ.
Method 1: Use the Student's t distribution with
d.f. = n − 1.
This is the method used in the text. It is widely employed in
statistical studies. Also, most statistical software packages use
this method.
Method 2: When n ≥ 30, use the sample standard
deviation s as an estimate for σ, and then use
the...

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2) a sample of size n equals 45 has a sample mean X equals 56.9
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construct a 99% confidence interval...

When σ is unknown and the sample is of size n
≥ 30, there are two methods for computing confidence intervals for
μ.
Method 1: Use the Student's t distribution with
d.f. = n − 1.
This is the method used in the text. It is widely employed in
statistical studies. Also, most statistical software packages use
this method.
Method 2: When n ≥ 30, use the sample standard
deviation s as an estimate for σ, and then use
the...

When σ is unknown and the sample is of size n ≥ 30, there are
two methods for computing confidence intervals for μ. Method 1: Use
the Student's t distribution with d.f. = n − 1. This is the method
used in the text. It is widely employed in statistical studies.
Also, most statistical software packages use this method. Method 2:
When n ≥ 30, use the sample standard deviation s as an estimate for
σ, and then use the...

Find the critical value
t/α2
needed to construct a confidence interval of the given level
with the given sample size. Round the answers to three decimal
places.
(a) For level
99.5%
and sample size
6
(b) For level
95%
and sample size
15
(c) For level
80%
and sample size
29
(d) For level
98%
and sample size
12

1.Given a sample size of n=19, what is the degree of freedom for
hypothesis testing and confidence intervals for mean
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QUESTION PART A: For a confidence level of 80% with a sample
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QUESTION PART B: Assume that a sample is used to estimate a
population mean μμ. Find the margin of error M.E. that
corresponds to a sample of size 13 with a mean of 46.5 and a
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Report ME accurate to one decimal place because the sample
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When ? is unknown and the sample is of size
n?30, there are two methods for computing confidence
intervals for ?.
Method 1: Use the Student's t distribution with
d.f.= n?1.
This is the method used in the text. It is widely employed in
statistical studies. Also, most statistical software packages use
this method.
Method 2: When n ? 30, use the sample standard
deviation sas an estimate for ?, and then use the
standard normal distribution.
This method is...

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