Question

- Which of the following statements is true?

- The 95% confidence interval is wider than the 99% confidence interval.
- The ONLY way to reduce the width of a confidence interval is to reduce the confidence level.
- The required sample size for a population mean is ONLY dependent on population variance.
- Given population variance and sampling error, higher confidence level results in larger sample size.

Answer #1

1- Which of the following statements is true?
I. For a certain confidence level, you get a higher margin of
error if you reduce your sample size.
II. For a given sample size, increasing the margin of error will
mean higher confidence.
III. For a fixed margin of error, smaller samples will mean
lower confidence.
I only
II only
III only
II and III only
All of them
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2- Which must be true about a 90% confidence interval based...

True or false?:
13) For a sample mean, the 99% confidence interval is wider than
the 95% confidence interval. 14) The larger the sample size the
more likely x̅ is close to μ.
15) Changing sample size has no effect on power when using the t
test.
16) For the independent two-sample t test, increasing sample
variances decreases power.

Which of the following is TRUE?
A.
The confidence interval is narrower if the sample size is
smaller.
B.
The confidence interval is narrower if the level of significance
is smaller.
C.
The confidence interval is wider if the level of confidence
level is larger.
D.
The confidence interval is wider if the sample size is
larger.

True or false:
1. When constructing a confidence interval for a sample
Mean, the t distribution is appropriate whenever the sample size is
small.
2. The sampling distribution of X (X-bar) is not always
a normal distribution.
3. The reason sample variance has a divisor of n-1
rather than n is that it makes the sample standard deviation an
unbiased estimate of the population standard
deviation.
4. The error term is the difference between the actual
value of the dependent...

The width of a confidence interval will be:
Narrower for 98 percent confidence than for 90 percent
confidence.
Wider for a sample size of 64 than for a sample size of 36.
Wider for a 99 percent confidence than for 95 percent
confidence.
Narrower for a sample size of 25 than for a sample size of
36.
None of these.

Sample mean is always:
The lower endpoint of the 99% confidence interval.
The middle of the confidence 99% interval.
The upper endpoint of the 99% confidence interval.
The average monthly electricity consumption in a random sample
of 100 households in February 2016 in North Kingstown was 637
kilowatt hours (kWh) with sample standard deviation s=45kwh. A 95%
confidence interval for the true electricity consumption in North
Kingstown is
637 ± 1.95 * 45/10
637 ± 1.96 * 45
637 ±...

Which of the following statements about confidence intervals are
true?
I. A 95% confidence interval will contain the true μ 95% of the
time.
II. If P(|X̅ − μ| > 3) = 0.035. Then a value of μ that is 3
or less units away from X̅ will be included in the 99% confidence
interval.
III. The point estimate X̅ will be included in a 99% confidence
interval.

What sample size is required to ensure the 99% confidence
interval has a width no greater than 20 when sampling from a
population with standard deviation of 30?

Calculate the 95% confidence interval for the difference
(mu1-mu2) of two population means given the following sampling
results. Population 1: sample size = 18, sample mean = 26.66,
sample standard deviation = 1.04. Population 2: sample size = 15,
sample mean = 10.79, sample standard deviation = 1.71.

Which of the following statements is true with
regards to a confidence interval?
Select one:
a. The true population value is always inside the constructed
interval
b. Most calculations of confidence intervals require a point
estimate and the margin of error
c. Given the same confidence level, building a t-interval is
always narrower than a z-interval
d. A 90% confidence interval means there is a 90% chance the
population value is within the constructed interval
e. You need to know...

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