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(What does "Endorsed by" mean?)Summary: This module provides an review on Chi-Square Distribution as a part of Collaborative Statistics collection (col10522) by Barbara Illowsky and Susan Dean.
The next two questions refer to the following real study:
A recent survey of U.S. teenage pregnancy was answered by 720 girls, age 12 - 19. 6% of the girls surveyed said they have been pregnant. (Parade Magazine) We are interested in the true proportion of U.S. girls, age 12 - 19, who have been pregnant.
Find the 95% confidence interval for the true proportion of U.S. girls, age 12 - 19, who have been pregnant.
The report also stated that the results of the survey are accurate to within ± 3.7% at the 95% confidence level. Suppose that a new study is to be done. It is desired to be accurate to within 2% of the 95% confidence level. What is the minimum number that should be surveyed?
2401
Given:
The next four questions refer to the following information:
Suppose that the time that owners keep their cars (purchased new) is normally distributed with a mean of 7 years and a standard deviation of 2 years. We are interested in how long an individual keeps his car (purchased new). Our population is people who buy their cars new.
60% of individuals keep their cars at most how many years?
7.5
Suppose that we randomly survey one person. Find the probability that person keeps his/her car less than 2.5 years.
0.0122
If we are to pick individuals 10 at a time, find the distribution for the mean car length ownership.
If we are to pick 10 individuals, find the probability that the sum of their ownership time is more than 55 years.
0.9911
For which distribution is the median not equal to the mean?
B
Compare the standard normal distribution to the student-t distribution, centered at 0. Explain which of the following are true and which are false.
The next five questions refer to the following information:
We are interested in the checking account balance of a twenty-year-old college student. We randomly survey 16 twenty-year-old college students. We obtain a sample mean of $640 and a sample standard deviation of $150. Let
Explain why we cannot determine the distribution of
If you were to create a confidence interval or perform a hypothesis test for the population mean checking account balance of 20-year old college students, what distribution would you use?
student-t with
Find the 95% confidence interval for the true mean checking account balance of a twenty-year-old college student.
What type of data is the balance of the checking account considered to be?
quantitative - continuous
What type of data is the number of 20 year olds considered to be?
quantitative - discrete
On average, a busy emergency room gets a patient with a shotgun wound about once per week. We are interested in the number of patients with a shotgun wound the emergency room gets per 28 days.
The next two questions refer to the following information:
The probability that a certain slot machine will pay back money when a quarter is inserted is 0.30 . Assume that each play of the slot machine is independent from each other. A person puts in 15 quarters for 15 plays.
Is the expected number of plays of the slot machine that will pay back money greater than, less than or the same as the median? Explain your answer.
greater than
Is it likely that exactly 8 of the 15 plays would pay back money? Justify your answer numerically.
No;
A game is played with the following rules:
Over the long run of playing this game, what are your expected earnings?
You will lose $5
Find whose score was the best, compared to his or her own class. Justify your answer numerically.
Becca
The next two questions refer to the following information:
A random sample of 70 compulsive gamblers were asked the number of days they go to casinos per week. The results are given in the following graph:
 |
Find the number of responses that were “5".
14
Find the mean, standard deviation, the median, the first quartile, the third quartile and the IQR.
Based upon research at De Anza College, it is believed that about 19% of the student population speaks a language other than English at home.
Suppose that a study was done this year to see if that percent has decreased. Ninety-eight students were randomly surveyed with the following results. Fourteen said that they speak a language other than English at home.
Assume that you are an emergency paramedic called in to rescue victims of an accident. You need to help a patient who is bleeding profusely. The patient is also considered to be a high risk for contracting AIDS. Assume that the null hypothesis is that the patient does not have the HIV virus. What is a Type I error?
We conclude that the patient does have the HIV virus when, in fact, the patient does not.
It is often said that Californians are more casual than the rest of Americans. Suppose that a survey was done to see if the proportion of Californian professionals that wear jeans to work is greater than the proportion of non-Californian professionals. Fifty of each was surveyed with the following results. 15 Californians wear jeans to work and 6 non-Californians wear jeans to work.
The next two questions refer to the following information:
A group of Statistics students have developed a technique that they feel will lower their anxiety level on statistics exams. They measured their anxiety level at the start of the quarter and again at the end of the quarter. Recorded is the paired data in that order: (1000, 900); (1200, 1050); (600, 700); (1300, 1100); (1000, 900); (900, 900).
This is a test of (pick the best answer):
C
State the distribution to use for the test.
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Last edited by Susan Dean on Jun 28, 2012 1:54 pm -0500.
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"Reviewer's Comments: 'I recommend this book. Overall, the chapters are very readable and the material presented is consistent and appropriate for the course. A wide range of exercises introduces […]"