Question

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 a list of formulas.)

What is the lower limit of the 90% confidence interval?

What is the upper limit of the 90% confidence interval?

Answer #1

Given that the life-time of a certain brand of battery is known to have a standard deviation of = 16 hours. Suppose that a random sample of n = 50 such batteries has a mean lifetime of =37.6 hours.

For the above-given details, the confidence interval is calculated as:

where Zc is critical Z score for normal distribution which is calculated using excel formula for normal distribution with the help of confidence level, the formula used is =NORM.S.INV(0.95) which results in Zc = 1.645

Now the confidence interval is calculated as:

So, the lower limit is 33.9 and the Upper limit is 41.3

The lifetime of a certain brand of electric light bulb is known
to have a standard deviation of
51
hours. Suppose that a random sample of
150
bulbs of this brand has a mean lifetime of
481
hours. Find a
90%
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 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...

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...

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...

The lifetime of a certain type of battery is known to be
normally distributed with a population standard deviation of 20
hours. A sample of 50 batteries had a mean lifetime of 120.1
hours.
a. What is the point estimate?
b. Calculate the sampling error.
c. Construct a 95% confidence interval for the population mean.
Explain the answer in a sentence.

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...

Problem Page A certain brokerage house wants to estimate the
mean daily return on a certain stock. A random sample of 14 days
yields the following return percentages: 0.89, -0.27, -2.76, 0.08,
2.29, 2.92, -0.21, -2.69, -2.46, 2.19, -1.58, 1.76, -1.77, 2.57 If
we assume that the returns are normally distributed, find a 95 %
confidence interval for the mean daily return on this stock. Then
complete the table below. Carry your intermediate computations to
at least three decimal places....

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%...

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,...

A random sample of 200 individuals working in a large city
indicated that 58 are dissatisfied with their working conditions.
Based upon this, compute a 90% confidence interval for the
proportion of all individuals in this city who are dissatisfied
with their working conditions. Then complete the table below. Carry
your intermediate computations to at least three decimal places.
Round your answers to two decimal places. (If necessary, consult a
list of formulas.)
What is the lower limit of the...

ADVERTISEMENT

Get Answers For Free

Most questions answered within 1 hours.

ADVERTISEMENT

asked 6 minutes ago

asked 17 minutes ago

asked 35 minutes ago

asked 37 minutes ago

asked 37 minutes ago

asked 38 minutes ago

asked 48 minutes ago

asked 57 minutes ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago