Question

1. Consider a normally distributed population with a standard deviation of 64. If a random sample of 90 from the population produces a sample mean of 250, construct a 95% confidence interval for the true mean of the population.

2.A psychologist is studying learning in rats (to run a maze). She has a sample of 40 rats and their mean time to run the maze if 5 minutes with a standard deviation of 1. Estimate the average time to run the maze with a 95% confidence interval.

Answer #1

The time it takes to complete one biology experiment is normally
distributed with known standard deviation of 20 minutes. A random
sample of 64 experiments in the science school in UCLA had a mean
time of 75 minutes. Find the standard error, margin of error, and
the upper and lower confidence limits of a 95% confidence interval
for the population mean, m.

A simple random sample of size n is drawn from a population that
is normally distributed. The sample mean, x overbar, is found to
be 109, and the sample standard deviation, s, is found to be
10.
(a) Construct a 95% confidence interval about mu if the
sample size, n, is 18.
(b) Construct a 95% confidence interval about mu if the
sample size, n, is 14.
(c) Construct a 90% confidence interval about mu if the
sample size, n,...

A simple random sample of 25 items from a normally distributed
population resulted in a sample mean of 80 and a sample standard
deviation of 7.5. Construct a 95% confidence interval for the
population mean.

A simple random sample of size
n=22
is drawn from a population that is normally distributed. The
sample mean is found to be
x overbar 69
and the sample standard deviation is found to be
s equals=20.
Construct a
90%
confidence interval about the population mean.
The
90%
confidence interval is
(?,?)

A simple random sample of size n is drawn from a population that
is normally distributed. The sample? mean, is found to be 112?, and
the sample standard? deviation, s, is found to be 10.
?(a) Construct a 95?% confidence interval about
mu? if the sample? size, n, is 18.
?(b) Construct a 95?% confidence interval about
mu? if the sample? size, n, is 11.
?(c) Construct a 70?% confidence interval about
mu? if the sample? size, n, is 18....

A simple random sample of size n=23 is drawn from a population
that is normally distributed. The sample mean is found to be x
bar=68 and the sample standard deviation is found to be s=15.
Construct a 90?% confidence interval about the population mean.
The 90?% confidence interval is ?(nothing?,nothing?).

A simple random sample of size nequals17 is drawn from a
population that is normally distributed. The sample mean is found
to be x overbar equals 61 and the sample standard deviation is
found to be sequals11. Construct a 95% confidence interval about
the population mean. The 95% confidence interval is ( nothing,
nothing). (Round to two decimal places as needed.)

A simple random sample of size nequals24 is drawn from a
population that is normally distributed. The sample mean is found
to be x overbar equals 58 and the sample standard deviation is
found to be sequals10. Construct a 90% confidence interval about
the population mean. The 90% confidence interval is ( nothing,
nothing). (Round to two decimal places as needed.)

A simple random sample of size n is drawn from a population that
is normally distributed. The sample mean, x overbar, is found to
be 105, and the sample standard deviation, s, is found to be 10.
(a) Construct a 95% confidence interval about mu if the sample
size, n, is 26. (b) Construct a 95% confidence interval about mu
if the sample size, n, is 20. (c) Construct an 80% confidence
interval about mu if the sample size, n,...

Construct a 95% confidence interval for the population standard
deviation σ of a random sample of 15 men who have a mean weight of
165.2 pounds with a standard deviation of 12.6 pounds. Assume the
population is normally distributed.

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