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# I really need help with this!!!! 2. A study of the time required

### Resolved Question:

I really need help with this!!!!
2. A study of the time required between landing clearance and physical touchdown for 35 randomly selected airplanes at City Airport showed the mean to be 280 seconds with a standard deviation of 19 seconds.

a) To construct an 90% confidence interval for the mean time required by all airplanes landing at City Airport, the formula that should be utilized is ____________________ (a list is provided below to make it easier to state your answer for this blank - please fill in the blank with the page number of the formula from the list below). If your answer to the preceding blank was i or ii then z/2=_____, or if your answer was iii then t/2= ______, however if your answer was iv or v, then chi-square values are ______ and ______.

b) The calculated value of the lower confidence interval limit is ______ and the upper confidence interval limit is ________.

c) The Air Traffic Controller Association stated that the confidence interval constructed above (your answer to part b) was too wide and the confidence level too low. This association wants to be 95% confident and accurate within 3 seconds of the true mean time. The minimum sample size needed, in order to meet the stated specifications, is ______.

3. It has been claimed that home sellers in State X generally receive less than the asking price when selling their home. The following data represents a random selection of six single-family homes in State X that recently sold for the prices (in thousands of dollars) listed below. To test the claim, using a 5% level of significance, answer the parts below. Also assume that the population distributions of prices are normally distributed.
#1 103 99
#2 227 224
#3 314 305
#4 140 140
#5 85 86
#6 295 275

a) The statement of hypothesis is Ho:__________ versus H1:________.

b) The distribution that can be justifiably utilized for this test is the _______________ (chi-square, F, t, z-standard normal) AND the critical value(s) from that distribution is/are ____________.

c) If the p-value is computed to be 0.063, then the appropriate decision to this test of hypothesis is to ___________ (reject Ho, not reject Ho), although there would exist the possibility of a _________________ (margin of error, standard error, Type I error, Type II error).

4. A psychologist suspects that windowless schools lead to anxiety in the psychological development of children. A random sample of children who are in windowless classrooms is selected and given an anxiety test. Higher scores indicate more anxiety. The same procedure is followed for a random selection of children in classrooms with windows. The results are shown below. By answering the following parts to this problem, test, using  = 0.01, that the anxiety scores for windowless school children is significantly different than that for school children in schools with windows.
Windowless Schools Schools with Windows
Mean 94 90
Standard Deviation 8 10
Sample Size 36 30

a) The statement of hypothesis is Ho:__________ versus H1:________.

b) The distribution that can be justifiably utilized for this test is the _______________ (chi-square, F, t, z-standard normal) AND the critical value(s) from that distribution is/are ____________.

c) The computed test statistic value is ___________, and the formula used to compute this test statistic value is _______________. (A list is provided below to make it easier to state your answer. Please fill in the blank with the page number of the formula from the list below.)

5. According to a loan association, 65% of college freshman have no declared major. Let's say it is believed that the percentage of UMUC freshman with an undeclared major is lower than 65%. In a random sample of 25 UMUC Freshman, 14 said that they have not yet declared a major. Test the claim that the percentage of UMUC freshman with an undeclared major is lower than 65% using alpha = 0.05 by answering the following.

a) State the null and alternative hypotheses. Ho:__________ and H1:________.

b) The distribution that can be justifiably utilized for this test is the _______________ (chi-square, F, t, z-standard normal) AND the critical value(s) from
Submitted: 3 years ago.
Category: Homework
Expert:  Susan Athena replied 3 years ago.

Is there a question 1?

In Question 2, can you please provide the list of formulas? formula names would be fine.

Thank you,
Susan
Customer: replied 3 years ago.

Thank you

Expert:  Susan Athena replied 3 years ago.
Customer: replied 3 years ago.

ok, thank you

Expert:  Susan Athena replied 3 years ago.
No worries!

Your study guide is below. Please let me know if you have any questions or problems. Also, note that question 5 was cut off - was there a part c?

Kind regards,
Susan

3.

b. t

2.015

c.

not reject H0

Type II error

4.

a.

H0: mu(windowless) <= mu(windows)

HA: mu(windowless)> mu(windows)

b.

distribution: t

critical value: 2.386

c.

test statistic: 1.806

Formula: t = (m1 - m2) / [s*(sqrt((1/n1) + (1/n2)))]

Let me know if this doesn’t match one of the formulae in your book. I used the “equal variances” formula, but your instructor might prefer you to use the unequal variances one.

5.

a. H0: p >= 0.65

HA: p < 0.65

b.

distribution: z-standard normal

critical value: -1.645

Customer: replied 3 years ago.

Oh thank you, XXXXX XXXXX working in #2 : ( here is the rest of the questions I didn't noticed that they were cut off

c) The computed test statistic value is ___________, and the formula used to compute this test statistic value is _______________. (A list is provided below to make it easier to state your answer. Please fill in the blank with the page number of the formula from the list below.)

i. page 514:

ii. page 427:

iii. page 496:

iv. page 484:

v. page 447:

vi. page 437:

vii. page 413: or

viii. page 474: or

6.In an audit of 30 randomly selected individual tax returns, 80% of them were required to pay additional taxes.

a) To construct a 95% confidence interval for the proportion of all individual tax returns that require payment of additional taxes, the formula that should be utilized is ____________________ (a list is provided below to make it easier to state your answer for this blank - please fill in the blank with the page number of the formula from the list below). If your answer to the preceding blank was i or ii then za/2=_____, or if your answer was iii then ta/2= ______, however if your answer was iv or v, then chi-square values are ______ and ______.

1. i. page 359:

2. ii. page 378:

3. iii. page 371:

4. iv. page 388 1st:

5. v. page 388 2nd:

b) The calculated value of the lower confidence interval limit is ______ and the upper confidence interval limit is ________.

c) An accounting firm stated that a more precise interval estimate of the true proportion of individual tax returns that require payment of additional taxes was needed. They want a margin of error of no more than 10%, and yet still retain a 95% confidence level. To achieve that the minimum sample size needed is ______.

7. The average weight of an adult dog is 23 kg with a standard deviation of 7 kg. A random sample of 10 adult Dalmatians had a mean weight of 25 kg with a standard deviation of 6 kg. Assume that the weights of all adult breeds of dogs follow a normal distribution.

a) To construct a 95% confidence interval for the standard deviation in all adult Dalmatian dog weights, the formula that should be utilized is ____________________ (a list is provided below to make it easier to state your answer for this blank - please fill in the blank with the page number of the formula from the list below). If your answer to the preceding blank was i or ii then za/2=_____, or if your answer was iii then ta/2= ______, however if your answer was iv or v, then chi-square values are ______ and ______.

1. i. page 359:

2. ii. page 378:

3. iii. page 371:

4. iv. page 388 1st:

5. v. page 388 2nd:

b) A kennel owner claims that the variance in adult Saint Bernard weights is greater than the 49 kg2 for all adult dogs in general. In a test of this claim at the 5% significance level, the critical value was found to be 31.41 and the test statistic value was computed to be 32.867, which indicates that the appropriate decision is to _____________________________ (reject Ho, not reject/accept Ho), and the corresponding conclusion is that the variance in adult Saint Bernard weights is _____

1. i. significantly less than that for all adult dogs.

2. ii. not significantly less than that for all adult dogs.

3. iii. significantly greater than that for all adult dogs.

4. iv. not significantly greater than that for all adult dogs.

5. v. significantly different from that for all adult dogs.

6. vi. not significantly different from that for all adult dogs.

c) It was also conjectured that the variance in the weights of the adult Saint Bernard is more than the variance in the weights of the adult Dalmatian. In a test of this claim, using random samples of 10 adult dogs of each of these breeds, the claim should be located in _________ (Ho, H1), and the distribution that can be justifiably utilized in a test of this claim is the _______________ (chi-square, F, t, z-standard normal).

Customer: replied 3 years ago.

I would like to know if you received the questions 5-7? I received a status that you disconnected. I appreciate your help.

Expert:  Susan Athena replied 3 years ago.
I did get your questions, thank you. Where the question asks for the page number of the formula, I'll just put in the name of the formula.

Kind regards,
Susan
Customer: replied 3 years ago.

I tried to copy the options of the formulas but is not letting me . For number 4 I was able to match it.

Off course I will add bonus! sorry for the inconvenience.

Expert:  Susan Athena replied 3 years ago.

You need to spend \$3 to view this post. Add Funds to your account and buy credits.
Category: Homework
Satisfied Customers: 4332
Experience: 10+ yrs teaching & tutoring. AP essay grader. 2 masters degrees. English, IT, business.
Expert:  Susan Athena replied 3 years ago.
Hi,Isabel. Just checking in to see how your statistics class is going. Remember that I'm always here to help; feel free to start a new question with my name on it. Kind regards, Susan

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