Due to the popularity of instant messaging and social​networking, informal elements such as emoticons​ (e.g., the symbol​":)" to represent a​ smile) and abbreviations​ (e.g., "LOL" for​"laughing out​ loud") have worked their way into​ teenagers' school writing assignments. A survey interviewed 900 randomly selected teenagers by telephone on their writing habits.​ Overall, 460 of the teenagers admitted using at least one informal element in school writing assignments. Based on the survey​ results, construct a 90​% confidence interval for the proportion of all teenagers who have used at least one informal element in school writing assignments. Give a practical interpretation of the interval.

The 90% confidence interval is ( _____, _______ ). (Round to three decimal places as needed.

The next two questions (18 and 19) refer to the following:

The heights of elementary school students are known to follow a normal distribution with mean 121 cm and standard deviation 5 cm.

Question 18 (1 point)

Saved

What is the 60^th percentile of heights of elementary school students?

Question 18 options:

Question 19 (1 point)

Saved

A random sample of eight elementary school students is selected. What is the probability that their average height is between 122 cm and 123 cm?

Question 19 options:

You have chosen biology as your college major because you would like to be a medical doctor. However, you find that the probability of being accepted to medical school is about 20 percent. If you are accepted to medical school, then your starting salary when you graduate will be $250,000 per year. However, if you are not accepted, then you would choose to work in a zoo, where you will earn $39,000 per year. Without considering the additional years you would spend in school if you study medicine or the time value of money.

1. What is your expected starting salary?

2. What is the standard deviation of that starting salary?

Discuss your experiences with cyber-bullying – either a personal experience or one you know of from peers or the media. How did the different roles (victim, bully, bully victim, bystanders, and “toadies”) present themselves in this experience?

Then, imagine you are on the school board and a vocal advocate against bullying. You have been asked to design a program that addresses bullying in your school. How would you approach this task? Describe four factors involved in a multifaceted school-based approach to cyber-bulling prevention. What specific components would be included in your program? Be sure to look at community factors as well as family considerations. Be specific and explain your answers.

Question 5 (1 point)
A high school math teacher believes that male and female students who graduated from the school perform equally well on SAT math test. She randomly chooses 10 male students and 10 female students who graduated from this school. The following are the SAT math scores of the 20 students:

Male: 23, 30, 27, 29, 22, 34, 36, 28, 28, 31
Female: 22, 33, 30, 28, 28, 31, 34, 25, 29, 21

Test the teacher's claim.

What is the p-value?

Question 5 options:

0.6268

0.0407

0.7223

0.0521

Ho: 72.7% of high school students (grade 9-12) do not get enough sleep at night. (minimum 8 hours)

Ha: 72.7% of high school students (grade 9-12) do get enough sleep at night.

Sample size:

Sample mean:

Sample deviation:

Record the hypothesis test. Use 5% level of significance Include 95% confidence interval on solution sheet.

Create graph to illustrates results.

Please type out answers.

A recent survey showed that in a sample of 100 elementary school teachers, 15 were single. In a sample of 180 high school teachers, 36 were single. Is the proportion of high school teachers who were single greater than the proportion of elementary teachers who were single? Use α = 0.01.a) State the hypotheses that need to be tested (using proper notation)

b) Calculate the pooled estimate of p.

c) Calculate the test statistic.

d) Calculate the P-value OR critical value.

e) Make a conclusion(IN CONTEXT) using the connection between the P-value and alpha level OR test statistic and critical value.

In a large midwestern university (the class of entering freshmen is 6000 or more students), an SRS of 100 entering freshmen in 1999 found that 20 finished in the bottom third of their high school class.  Admission standards at the university were tightened in 2000.  In 2001, an SRS of 100 entering freshmen found that 10 finished in the bottom third of their high school class.  Let p1 and p2 be the proportion of all entering freshmen in 1999 and 2001, respectively, who graduated in the bottom third of their high school class.

Is there evidence that the proportion of freshmen who graduated in the bottom third of their high school class in 2001 has been reduced, as a result of the tougher admission standards adopted in 2000, compared to the proportion in 1999?  To determine this, you test the hypotheses

H0: p1 = p2, Ha: p1 > p2.

The z-test statistic is approximately 1.98, find the P-value, using a Standard Normal Table or your calculator.

Carolyn Shaw is 27. - She works as an accountant for an oil company. - Her salary next year will be $80,000. - She expects to receive a 5 percent raise each year until she retires at age of 65. - Carolyn is considering a return to school to pursue an MBA degree. - She expects the cost of books, tuition, and fees to be $70,000 the first year and $72,000 the second. - These costs are paid at the beginning of the year (as you surely know). - She will not work while in school. - Graduates of the school Carolyn is considering receive starting salaries that average $130,000. - Raises average 7 percent per year. - Carolyn considers the opportunity costs to be 12 percent. a)Determine the present value of Carolyn’s lifetime earnings if she does not return to school. b)Determine the present value of Carolyn’s lifetime earnings with an MBA degree. Remember, she won’t start her job for two years. c) What is the NPV of an MBA degree given Carolyn Shaw's assumptions?