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Steve
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Experience:  I teach Calculus and Probability in a University since 1994
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hello. i have several questions on stats and probability. they

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hello. i have several questions on stats and probability. they deal with hypothesis testing regarding a parameter, and estimating the value of the parameter. do you have time to do them or are you busy?
Hi,

I can help you

Can you post them here ?

Thanks
Customer: replied 3 years ago.
I'll have them ready by tomorrow afternoon.
Ok,

How many questions are ? multiple choice ?

Thanks
Customer: replied 3 years ago.
5 are multiple choice. But there's questions that have questions within them. Like theres question 1, then within question 1 there's question a, question b, etc.
Ok,

Post them tomorrow here and i will help you

Thanks
Customer: replied 3 years ago.

Here's some of the questions.


 


1. what is the area under the standard normal curve that lies to the left of Z=0.95?


 


2. what is the area under the standard normal curve that lies to the right of Z= -1.26


 


3. what is the area under the standard normal curve between Z subscript 1=1.96 and Z subscript 2=-1.96


 


4. Find the Z-score such that the area under the standard normal curve to the left of the score is 0.5636.


 


5. determine Mu of x bar and sigma of x bar given the data below.


Mu=63, sigma=18, n=36


 


6. A simple random sample of size n is drawn from a population standard deviation is known to be 5.1. the sample mean, x bar, is determined to be 25.8


a. compute the 95% confidence interval about Mu if the sample size n=50


 


b. compute the 95% confidence interval about Mu if the sample size n=80


 


c. how does the sample size affect the margin of error?


A. as the sample size increases, the margin of error decreases


B. as the sample size increases, the margin of error stays the


same.


C. as the sample size decreases, the margin of error decreases.


 


d. compute a 99% confidence interval about Mu if the sample size n=50


 


e. how does the increasing the level of confidence affect the size of margin of error?


A. as the % confidence increases, the margin of error


increases


B. as the % confidence increases, margin of error stays the


same


C. as the % confidence decreases, margin of error increases


 


f. compare the 99% confidence interval to the 95% confidence interval.


A. as the % confidence increases, the size of the interval stays


the same


B. as the % confidence increases, the size of the interval


increases


C. as the % confidence decreases, size of the interval


increases


 


7. A random variable X is normally distributed with mu= 20 and sigma=4.


a. compute (z subscript 1= x subscript 1 – mu divided by


sigma) for x subscript 1=14


 


b. compute (z subscript 2= x subscript 2 – mu divided by


sigma) for x subscript 2=21


 


c. the area under the normal curve between x subscript 1=14


and x subscript 2=21 is 0.5319. what is the area between Z’s


of 1 and Z’s of 2.


 


8. assume that the random variable X is normally distributed with a mean of mu=48 and a standard deviation of sigma=6


what is P(38<X<68)?


 


9. sketch and label a normal curve for the data in #8.


 


10. the number of peppermints in a 1 pound bag of the candy is normally distributed with a mean of 75 and a standard deviation of 9 candies.


a. whats the probability that a randomly selected bag contains


fewer than 65 peppermints?



b. whats the probability that a randomly selected bag contains


between 60 and 85?


 


c. what proportion of bags contains more than 70 peppermints?


 


11. the amount of time adults spend online is closely monitored by firms because this helps to determine ad costs.


a. do YOU THINK the variable “daily time spent online” would


be normally distributed, yes or no?


 


b. if you chose “no” for part a, what shape would you expect


the variable to have?


A. skewed left


B. skewed right


C. symmetric


D. uniform


Continuation of #11: further, this survey tells us that adults spend 1.75 hours/day online on a weekday. Assume that the standard deviation for “daily time spent online” is 0.75 hours. If a random sample of n=50 adults is obtained, describe the sampling distribution of x bar, the mean amount of daily spent online.


 


For the continuation, x bar is approximately normal with Mu of x bar= , and sigma of x bar= .



12. use the data in #11 to complete this problem.


 


Determine the probability that a random sample of 50 adults results in a mean “daily time spent online” of between 1.5 and 2 hours.


 


13. According to a study conducted by a statistical organization, the proportion of americans who are satisfied with the way things are going in their lives is 0.92. suppose that a random sample of 100 americans is obtained.


a. describe the sampling distribution of p hat. Choose the


correct answer.


A.distribution of p hat is approximately normal with(Mu


of p hat=0.92 and sigma of p hat=0.027)


 



B. distribution of p hat is approximately normal with (Mu


of p hat=0.92 and sigma of p hat=0.054)


 


C. distribution of p hat is binomial with n=100 and p=0.92


D. Distribution of p hat is uniform.


 


b. what is the probability that at least 85 americans in the sample are


satisfied with their lives?


 


c. whats the probability that 90 or fewer americans in the sample are


satisfied with their lives?

Ok,

But how many questions are ?

Thanks
Customer: replied 3 years ago.
There's a total of 13. They're numbered 1-13

Ok,

 

I will post the answers asap tonight

Thanks

Customer: replied 3 years ago.
Yes
But you said that these are some questions, do you have more ?

I can do them in this post, and if you need more you can open anew post

Is that ok ?

Thanks
Customer: replied 3 years ago.
Ok
I am working on them

Do you need to show work for the questions that are not multiple choice ?

Customer: replied 3 years ago.
Yes.
Oh ! that`s a lot of work

At this price i can do 1 to 6 (with work) , is that ok ?

Let me know....

Thanks
Customer: replied 3 years ago.
For this price, You can do 1-6 with work and the others without work
Let me check them agian, wait a minute

Thanks
I have some doubts with question 11)

So i can do:

1 to 6 (with work)

7,8,9,10,12 and 13 (without work)

Is that ok ?

Thanks
Customer: replied 3 years ago.
What do u mean by "without work"?
without work = only the answers for them

Let me know
Customer: replied 3 years ago.
So your saying your going to guess?
No !!!!

The right answers but without showing the steps
Customer: replied 3 years ago.
Ok.
OK,

I will start now, i will post the answers in less than 1 hour

Thanks
Customer: replied 3 years ago.
Are you sure you can do them in less than an hour?
about 1 hour, yes
Customer: replied 3 years ago.
I can wait till tomorrow. I'm not in a rush.
Ok,

in that case i will post the answers tonight or tomorrow morning

Thanks
Customer: replied 3 years ago.
Alright

Note: i did a little more (i did 11) b) too)

Check question 6) e) i think that the right option has a mistake

Here are the answers

Thanks

Steve
Customer: replied 3 years ago.
You didn't answer #5 and 11- a and 11-b
Yes, we stated that i had doubts about 11) we agreed not to do it , i did part b) of 11

I will check question 5)

wait a minute

Thanks

I am checking it, maybe you do not see the work for those questions because they have some equations

I will post a pdf file now

remember that i said that i have doubts about 11) ??

Thanks

Here are the answers into a pdf file

Sorry for any confusion

Thanks
Tell me if you still have any comment or doubt and remember to check
question 6) e)

Thanks
Customer: replied 3 years ago.
Did you already #5?
Yes, it is done

check the pdf file, did you see it there ?

Thanks

Customer: replied 3 years ago.
No

 

Are you talking about this question ?

 

5. determine Mu of x bar and sigma of x bar given the data below.


Mu=63, sigma=18, n=36

 

The answer is done (with work) tell me if you do not see it

 


Customer: replied 3 years ago.
I do not see it
Ok,

I will post it again here

wait a minute

Thanks

Or try this file (question 5)

Thanks

Customer: replied 3 years ago.
What's the answer to part b #11?
you see 5 ) now ??

I will check 11 b)

Thanks
Customer: replied 3 years ago.
I already seen #5. I need #11 b
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I am not sure about 11, maybe another option can be:

11)
a) No
b) skewed right

Thanks

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