Question

For the population of
infants subjected to fetal surgery for congenital anomalies, the
distribution of gestational ages at birth is approximately normal
with unknown mean μ and standard deviation σ. A random sample of 16
such infants has mean gestational age x̅ = 32.9 weeks and standard
deviation *s* = 4.5 weeks.

- Construct a 95% confidence interval for the true population mean μ.
- What is the length of this interval?
- How large a sample would be required for the 95% confidence interval to have length 3 weeks? Assume that the population standard deviation σ = 4.5 weeks.
- How large a sample would be needed for the 95% confidence interval to have length 2 weeks? Assume that the population standard deviation σ = 4.5 weeks.

Answer #1

The 95% confidence interval for all the mean
weight of infants born to mothers who smoke is µ = 5.40 to 6.80
pounds. The mean weight for a random sample of 25 newborns in this
region is 7.2 pounds with a standard deviation (s) of 0.85 pounds.
Is the birth weight of the infants in this sample significantly
different from that of the general population at α=0.05? (10
points) Explain your response (4 pts).
Please show work . Thank you...

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unknown standard deviation σ .
We want to estimate μ based on our sample.
A 95% confidence interval for the population mean birth weight
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A random sample of 24 recent birth records at the local hospital
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interval for the population mean birth weight based on these data
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A random sample of 125 items is drawn from a population whose
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(a)
Construct an interval estimate for μ with 95 percent
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The 95% confidence interval is from _________ to
__________
(b)
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The 95% confidence...

1. For a standard normal distribution, given:
P(z < c) = 0.9353
Find c.
2. A population of values has a normal distribution with
μ=195.6μ=195.6 and σ=42.9σ=42.9. You intend to draw a random sample
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What is the mean of the distribution of sample means?
μ¯x=μx¯=
What is the standard deviation of the distribution of sample
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(Report answer accurate to 2 decimal places.)
σ¯x=σx¯=
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A 95% confidence interval for μ using the sample results
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Round your answer for the point estimate to one decimal place,
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1. A sample of 35 circuits from a large normal population has
a mean resistance of 2.35 ohms. We know from past testing that
the
a) population standard deviation is 0.45 ohms. b) population
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Determine a 95% confidence interval for the true mean
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b)Arandomsampleofn=22has x=48ands=9.
c)Arandomsampleofn=20has x=45ands=8.
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