Question

Based on a sample of 100 customers, a company constructed a
confidence interval with a 90% confidence level of (25.1, 114.3)
for the mean annual income of its customers, in thousands of
dollars per year. Check *all* of the following that are true
about the confidence interval:

Calculation of the confidence interval assumed annual income is normally distributed. | ||

There is a 90% chance that the mean annual income of the customer population is between 25.1 and 114.3. | ||

The confidence interval would change if the company constructed it from a different sample of 100 customers. | ||

An 80% confidence interval calculated from the same sample would result in tighter confidence interval. |

Answer #1

**Solution;-**

**False - Calculation of the confidence interval assumed
annual income is normally distributed.**

The distribution for the mean annual income is not mentioned.

**True -** There is a 90% chance that the mean
annual income of the customer population is between 25.1 and
114.3.

**False -** The confidence interval would change if
the company constructed it from a different sample of 100
customers.

Approximately same confidence interval would be obtained.

**True - An 80% confidence interval calculated from the
same sample would result in tighter confidence
interval.**

The value for confidence coefficient for 80% confidence level would be smaller than confidence coefficient for 90% confidence level, hence 80% confidence interval calculated from the same sample would result in tighter confidence interval.

Based on a simple random sample of size 90, an 84% confidence
interval for the unknown mean SAT MATH score, μμ, in some large
population is 517<μ<525517<μ<525.
Which of the following is/are correct interpretation(s) of this
confidence interval?There may be more than one correct answer; you
must check all correct answers in order to get credit for this
problem.
A. 84% of individuals in this sample have a mean
SAT MATH score between 517 and 525.
B. 84% of individuals...

Confidence Interval Examples 1. A recent survey based on 100
TCOB undergraduates showed that 40% of the respondents were using
an Iphone. What is the 90% confidence interval for the proportion
of Iphone users among TCOB undergraduates? (1) What is the
corresponding Z-‐value? (2) What is the sampling error for the
proportion? (3) What is the confidence interval? 2. A sample study
of 100 customers of Best Buy showed that the average dollar
spending during the last three months was...

Find a 90% confidence interval for a population mean ?
for these values. (Round your answers to three decimal places.)
(a)
n = 130, x = 0.85, s2 =
0.084
to
(b)
n = 40, x = 20.1, s2 =
3.86
to
(c)
Interpret the intervals found in part (a) and part (b).
There is a 10% chance that an individual sample proportion will
fall within the interval.In repeated sampling, 10% of all intervals
constructed in this manner will enclose...

An SRS yields a sample mean, x ̅, of 8.6. A 90% confidence
interval from the same data is 8.6 ± 2.4. Which of the following
statements is true about the situation?
(A) If the population mean were 5.2, the sample mean
of 8.6 would be highly likely.
(B) If the population mean were 5.2, the sample mean
of 8.6 would be highly unlikely.
(C) There is a 90% chance that the population mean
lies between 6.2 and 11.0
(D) ...

Find a 90% confidence interval for a population mean ?
for these values. (Round your answers to three decimal places.)
(a)
n = 145, x = 0.88, s2 =
0.084
to
(b)
n = 70, x = 25.6, s2 =
3.49
to
(c)
Interpret the intervals found in part (a) and part (b).
There is a 10% chance that an individual sample proportion will
fall within the interval.There is a 90% chance that an individual
sample proportion will fall within...

A sample is selected to find a 90% confidence interval for the
average starting salary. Here are the sample statistics: n = 31, x¯
= $43, 780, s = $1, 600. a). Find the t− score used in the
calculation of the confidence interval.
b). Build a 90% confidence interval for the mean starting
salary.
c). Based on the result of part b), could we make a conclusion
that the mean staring salary is below $45, 000? Explain your
reason.

A manufacturer is interested in
estimating the lifetime of printers. A confidence interval is
constructed based on a sample of 20 printers and the assumption
that the population distribution of the lifetime of a printer is
normal.
If the population standard deviation is 1.5 and the
upper end of a 95% confidence interval is 6.36, find the observed
sample mean (show your final answer correct to two decimal
places).
If, instead, we only know the sample standard
deviation (which is...

A student was asked to find a 90% confidence interval for the
proportion of students who take notes using data from a random
sample of size n = 88. Which of the following is a correct
interpretation of the interval 0.1 < p < 0.3?
Check all that are correct.
The proprtion of all students who take notes is between 0.1 and
0.3, 90% of the time.
There is a 90% chance that the proportion of notetakers in a
sample...

A student was asked to find a 90% confidence interval for the
proportion of students who take notes using data from a random
sample of size n = 84. Which of the following is a correct
interpretation of the interval 0.1 < p < 0.31? Check all that
are correct. With 90% confidence, a randomly selected student takes
notes in a proportion of their classes that is between 0.1 and
0.31. There is a 90% chance that the proportion of...

Suppose a 90% confidence interval, based upon a sample of size
35, for the mean number of hours that college students spend on
social media each week was 25 to 35 hours. The sample standard
deviation from this previous study was 17.9. How many students
should be surveyed in order to cut the width of the interval down
from 10 hours to 5 hours? Group of answer choices A.100 B.300 C.250
D.139

ADVERTISEMENT

Get Answers For Free

Most questions answered within 1 hours.

ADVERTISEMENT

asked 3 minutes ago

asked 13 minutes ago

asked 14 minutes ago

asked 30 minutes ago

asked 33 minutes ago

asked 39 minutes ago

asked 41 minutes ago

asked 49 minutes ago

asked 49 minutes ago

asked 49 minutes ago

asked 58 minutes ago

asked 1 hour ago