Question

A psychologist wants to estimate the standard deviation of IQ scores. It is widely believed that IQ scores follow a normal distribution. Her random sample of 25 IQ scores has a mean of 97.4 and a standard deviation of 17.2. Find the 99% confidence interval for the population standard deviation based on this sample. Then complete the table below. Carry your intermediate computations to at least three decimal places. Round your answers to at least two decimal places. (If necessary, consult a list of formulas.)

What is the lower limit of the 99% confidence interval?

What is the upper limit of the 99% confidence interval?

Answer #1

A psychologist wants to estimate the standard deviation of IQ
scores. It is widely believed that IQ scores follow a normal
distribution. Her random sample of
25
IQ scores has a mean of
99
and a standard deviation of
13.2
. Find the
99%
confidence interval for the population standard deviation based
on this sample. Then complete the table below.
Carry your intermediate computations to at least three decimal
places. Round your answers to at least two decimal places. (If...

An existing inventory for a test measuring self-esteem indicates
that the scores have a standard deviation of 8. A psychologist gave
the self-esteem test to a random sample of 70 individuals, and
their mean score was 62. Construct a 95% confidence interval for
the true mean of all test scores. Then complete the table below.
Carry your intermediate computations to at least three decimal
places. Round your answers to one decimal place. (If necessary,
consult a list of formulas.)
What...

Lifetimes of AAA batteries are approximately normally
distributed. A manufacturer wants to estimate the standard
deviation of the lifetime of the AAA batteries it produces. A
random sample of
21
AAA batteries produced by this manufacturer lasted a mean of
11
hours with a standard deviation of
1.7
hours. Find a
95%
confidence interval for the population standard deviation of the
lifetimes of AAA batteries produced by the manufacturer. Then
complete the table below.
Carry your intermediate computations to at...

A psychologist is interested in the mean IQ score of a given
group of children. It is known that the IQ scores of the group have
a standard deviation of 12. The psychologist randomly selects 80
children from this group and finds that their mean IQ score is 112.
Based on this sample, find a 90% confidence interval for the true
mean IQ score for all children of this group. Then complete the
table below.
Carry your intermediate computations to...

Lifetimes of AAA batteries are approximately normally
distributed. A manufacturer wants to estimate the standard
deviation of the lifetime of the AAA batteries it produces. A
random sample of 28 AAA batteries produced by this manufacturer
lasted a mean of 9.1 hours with a standard deviation of 2.2 hours.
Find a 95% confidence interval for the population standard
deviation of the lifetimes of AAA batteries produced by the
manufacturer. Then complete the table below. Carry your
intermediate computations to at...

The union for a particular industry has determined that the
standard deviation of the daily wages of its workers is $
19
. A random sample of
150
workers in this industry has a mean daily wage of $
112
. Find a
99%
confidence interval for the true mean daily wage of all union
workers in the industry. Then complete the table below.
Carry your intermediate computations to at least three decimal
places. Round your answers to one decimal...

The scores on an examination in economics are approximately
normally distributed with mean 500 and an unknown standard
deviation. The following is a random sample of scores from this
examination. 422, 437, 472, 502, 534 Send data to Excel Find a 90%
confidence interval for the population standard deviation. Then
complete the table below. Carry your intermediate computations to
at least three decimal places. Round your answers to at least two
decimal places. (If necessary, consult a list of formulas.)...

The lifetime of a certain brand of electric light bulb is known
to have a standard deviation of 53 hours. Suppose that a random
sample of 100 bulbs of this brand has a mean lifetime of 481 hours.
Find a 99% confidence interval for the true mean lifetime of all
light bulbs of this brand. Then complete the table below. Carry
your intermediate computations to at least three decimal places.
Round your answers to one decimal place. (If necessary, consult...

The lifetime of a certain brand of battery is known to have a
standard deviation of 16 hours. Suppose that a random sample of 50
such batteries has a mean lifetime of 37.6 hours. Based on this
sample, find a 90% confidence interval for the true mean lifetime
of all batteries of this brand. Then complete the table below.
Carry your intermediate computations to at least three decimal
places. Round your answers to one decimal place. ( If necessary,
consult...

estion
The standard deviation of the daily demand for a product is an
important factor for inventory control for the product. Suppose
that a pharmacy wants to estimate the standard deviation of the
daily demand for a certain antibiotic. It is known that the daily
demand for this antibiotic follows an approximately normal
distribution. A random sample of
23
days has a sample mean of
125
orders for this antibiotic with a standard deviation of
10.1
orders. Find a
95%...

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