# 8.11 Confidence interval lab 4

 Page 1 / 1
This lab incorporate both lab 1 and lab 2 with minitab.

Confidence Interval Lab

Name:

## Student learning outcomes:

• The student will calculate the 90% confidence intervals.
• The student will interpret confidence intervals.
• The student will examine the effects that changing conditions has on the confidence interval.
• The student will examine the relationship between the confidence level and the percent of constructed intervals that contain the population average.

## Collect the data

Check the Real Estate section in your local newspaper or website. (Note: many papers only list them

one day per week. Also, we will assume that homes come up for sale randomly.) Record the

sales prices for 36 randomly selected homes recently listed in the county and indicate whether you found them in the paper or on the website. Include the reference.

Complete the table:

## Describe the data

1. Compute the following: (include the session window)

$\overline{x}$ = s = n =

2. Define the Random Variable $\overline{X}$ in words:

3. State the estimated distribution to use. Use both words and symbols.

## Find the confidence interval

1. Using Minitab, calculate the 90% confidence interval and determine the error bound. (include in the session window)

a. Confidence Interval:

b. Error Bound:

2. How much area is in both tails (combined)? α =

3. How much area is in each tail? $\frac{\alpha }{2}$ =

4. Using Minitab, create the graph for the 90% confidence interval created above. (Graph → Prbability Distribution Plot→View Probability) Include the graph with this lab.

5. Some students think that a 90% confidence interval contains 90% of the data. Use the list of data on the first page and count how many of the data values lie within the confidence interval. What percent is this? Is this percent close to 90%? Explain why this percent should or should not be close to 90%.

6. How many house prices would be needed in the sample to ensure that the error was no more than \$2000 for the 90% confidence interval?

## Describe the confidence interval

1. In two to three complete sentences, explain what a Confidence Interval means (in general), as if you were talking to someone who has not taken statistics.

2. In one to two complete sentences, explain what this Confidence Interval means for this particular study.

## Use the data to construct confidence intervals

1. Using the above information, construct a confidence interval for each confidence level given. (include the session window information)

 Confidence Level Error Bound Confidence Interval 85% 95% 98% 99%

2. What happens to the EBM as the confidence level increases? Does the width of the confidence interval increase or decrease? Explain why this happens.

## Effect of an outlier

Suppose one of the values input incorrectly. Choose one data value and increase the amount by adding two extra zeroes. (include in the session window)

1. Calculate the 90% confidence interval: _____________

2. Calculate the Error Bound: ____________

3. How does the outlier affect the width of the confidence interval? Use complete sentences.

## Part ii

Heights of 100 Women (in Inches)

 59.4 63.8 61.8 61.3 61.5 62.9 64.3 60.8 57.9 64 71.6 62.9 60.6 59.2 64.3 63.1 65 65.5 58.5 66.4 69.3 63 69.8 64.1 62.9 62.2 64.1 62.3 63.4 61.2 65 63.9 60 59.3 60.6 58.7 61.1 65.5 69.2 60.4 62.9 68.7 64.9 64.9 63.8 64.7 65.3 64.7 65.9 58.7 66.5 65.5 66.1 62.4 58.8 66 64.6 58.8 62.2 66.7 61.7 61.9 66.8 63.5 64.9 60.5 59.2 66.1 60 67.5 55.2 69.6 60.6 60.9 65.7 64.7 61.4 64.9 58.1 63.2 67.2 58.7 65.6 63.3 62.5 65.4 62 66.9 62.5 56.6 66.5 63.4 63.8 66.3 70.9 60.2 63.5 57.9 62.4 67.7

1. Listed above are the heights of 100 women. These are in the student data file in the lab. Use MiniTab to randomly select 10 data values. (Calc → Random data → data from a column)

2. Calculate the sample mean and sample standard deviation and record our answer below. Assuming that the population standard deviation is known to be 3.3. Construct a 90% confidence interval for your sample of 10 values. Write the confidence interval you obtained below.

3. Repeat #1 and #2 nine more times, and record the 90% confidence interval for each of your samples. (Note: since you are randomly selecting the 10 data values you may use the same one in more than one sample. Include this portion of your session window)

• $\overline{x}$ = s = CI =
• $\overline{x}$ = s = CI =
• $\overline{x}$ = s = CI =
• $\overline{x}$ = s = CI =
• $\overline{x}$ = s = CI =
• $\overline{x}$ = s = CI =
• $\overline{x}$ = s = CI =
• $\overline{x}$ = s = CI =
• $\overline{x}$ = s = CI =
• $\overline{x}$ = s = CI =

## Discussion questions

1. The actual population mean for the 100 heights given above is μ = 63.3. Using the samples above, for how many intervals does the value of μ lie between the endpoints of the confidence interval? .

2. What percentage of the total number of confidence intervals generated contain the mean μ?

3. Is the percent of confidence intervals that contain the population mean μ close to 90%?

4. Suppose we had generated 100 confidence intervals. What do you think would happen to the percent of confidence intervals that contained the population mean? Use 2 – 3 complete sentences.

5. When we construct a 90% confidence interval, we say that we are 90% confident that the true population mean lies within the confidence interval. Using complete sentences, explain what we mean by this phrase in terms a non-statistician would understand.

6. Some students think that a 90% confidence interval contains 90% of the data. Use the first confidence interval calculated and count how many of the 100 data values lie within that confidence interval? What percent is this? Is this percent close to 90%? Using 3 – 4 sentences to explain why it should or should not be close to 90%.

how can chip be made from sand
is this allso about nanoscale material
Almas
are nano particles real
yeah
Joseph
Hello, if I study Physics teacher in bachelor, can I study Nanotechnology in master?
no can't
Lohitha
where is the latest information on a no technology how can I find it
William
currently
William
where we get a research paper on Nano chemistry....?
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
revolt
da
Application of nanotechnology in medicine
has a lot of application modern world
Kamaluddeen
yes
narayan
what is variations in raman spectra for nanomaterials
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
how did you get the value of 2000N.What calculations are needed to arrive at it
Privacy Information Security Software Version 1.1a
Good
Got questions? Join the online conversation and get instant answers!