A researcher investigating sex role stereotypes and occupational aspirations drew a random sample of 125 female university students. She discovered that 55 plan to go on to graduate school. Construct the 90% confidence interval for the true proportion of women seeking higher education. Show your work.
In 1992, the FAA conducted 86,991 pre-employment drug tests on job applicants who were to be engaged in safety and security-related jobs, and found that 1,143 were positive. (a) Construct a 95 percent confidence interval for the population proportion of positive drug tests. (b) Why is the normality assumption not a problem,
A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was weighed on a very accurate scale. The results in grams were 3.087 3.131 3.241 3.241 3.270 3.353 3.400 3.411 3.437 3.477 (a) Construct a 90 percent confidence interval for the true mean weight. (b) What sample size would be necessary to estimate
Dr. Patton is a Professor of English. Recently he counted the number of misspelled words in a group of student essays. For his class of 40 students, the mean number of misspelled words was 6.05 and the standard deviation 2.44 per essay. Construct a 95 percent confidence interval for the mean number of misspelled words in the pop
A sample of 20 pages was taken without replacement from the 1,591-page phone directory Ameritech Pages Plus Yellow Pages. On each page, the mean area devoted to display ads was measured (a display ad is a large block of multicolored illustrations, maps, and text). The data (in square millimeters) are shown below: Add new rows
8.64 Biting an unpopped kernel of popcorn hurts! As an experiment, a self-confessed biting an unpopped kernel of popcorn hurts! As an experiment, a self-confessed connoisseur of cheap popcorn carefully counted 773 kernels and put them in a popper. After popping, the unpopped kernels were counted. There were 86. (a) Construct a
8.46 A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was weighed on a very accurate scale. The results in grams were 3.087 3.131 3.241 3.241 3.270 3.353 3.400 3.411 3.437 3.477 8.62 In 1992, the FAA conducted 86,991 pre-employment drug tests on job applicants who were to be engaged in safet
A toy manufacturer wants to see how long, on average, a new toy captures children's attention. He tests 14 children selected at random and finds that their mean attention span is 23 minutes with a standard deviation of 7 minutes. If we assume that attention spans are normally distributed, find a 99% confidence interval for the m
The breaking strengths of cables produced by a certain manufacturer have a standard deviation of 92 pounds. A random sample of 70 newly manufactured cables has a mean breaking strength of 1900 pounds. Based on this sample, find a 95% confidence interval for the true mean breaking strength of all cables produced by this manufact
In an article in the Journal of Management, Morris, Avila and Allen studied innovation by surveying firms to find the number of new products introduced by the firms. A random sample of 100 California based firms are selected. Each firm is asked to report the number of new products introduced last year. The survey found that
4) A building developer has the opportunity to purchase several acres of land that is divided up into several lots for building single-family homes. It is known that the average sale price of all of the lots is $80,000 and the standard deviation of the sale price is $12,000. What can you say about the percentage of lots that ha
In an article in the Journal of Management, Morris, Avila and Allen studied innovation by surveying firms to find the number of new products introduced by the firms. A random sample of 100 California based firms are selected. Each firm is asked to report the number of new products introduced last year. The survey found that
5. State the main points of the Central Limit Theorem for a mean. 6. Why is population shape of concern when estimating a mean? What does sample size have to do with it?" (Doane and Seward, p. 338) Exercise 8.46 A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was weighed on a very accur
Please find the problems attached.
Explain why a confidence interval for a predictor coefficient is equivalent to a 2-tailed test of significance?
For a random sample of 10 fifth generation iPod music players, the mean battery life was 9.47 hours with a standard deviation of 2.14 hours. a. Construct a 95% confidence interval for the mean number of hours the batteries will last on these players. b. Suppose you wanted more accuracy, what could you do to increase the
A survey conducted during May 20 - 22, 2005, asked 1006 Americans, "During the past year, about how many book, either hardcover or paperback, did you read either all or part of the way through?" Results of the survey indicated that the mean of the sample was 13.4 books with a standard deviation of 16.6 books. Construct a 99% c
1. The following sample of 16 measurements was selected from a population that is approximately normally distributed: 91 80 99 110 95 106 78 121 106 10 97 82 100 83 115 104. Construct a 95% confidence interval for the population mean. 2. In a survey of 1000 persons, 290 responded that they approve of the president's job perfo
1) The diameter of Ping- Pong balls manufactured at a large factory is expected to be approximately normally distributed with a mean of 1.30 inches and a standard deviation of 0.40 inch. What is the probability that a randomly selected Ping-Pong ball will have a diameter between 1.31 and 1.33 inches? A) 0.0987 (B) 0.1747 (C) 0.
Please see the attached file. 1. What is the appropriate critical value for each of the following confidence levels and sample sizes? (Remember that in regard to confidence level this implies two-tails) (a) Critical z-value for an 85% confidence level for sample of size n = 36: (b) Critical t-value for
1) If you were constructing a 99% confidence interval of the population mean based on a sample of n=25 where the standard deviation of sample s = 0.50, the critical t will be: A) 2.7969 (B) 2.7874 (C) 2.4922 (D) 2.4851 2) A statistician wishes to estimate the average total compensation of CEOs in the service industry. Data w
ACME Lumber Company selects a random sample of 36 customers. Customers are rated on their annual spend at ACME Lumber Stores. During an account review, history showed a mean of $32,000, along with a standard deviation of $18,200. What is the 90% Confidence Interval for the mean account valuation of the population of customers
Please see the attached file.
Please provide the evidence of your work. Thank you. (Confidence Interval...Please use Excel to solve this...or if hand work is faster, then please go ahead...But please provide the evidence of your work. )
Assume that in a hypothesis test with null hypothesis = 13.0 at 0.05, that a value of 11.0 for the sample mean results in the null hypothesis not being rejected. That corresponds to a confidence interval result of A. The 95% confidence interval for the mean does not contain the value 13.0 B. The 95% confidence interval for
Use the traditional method to test the given hypothesis. Assume that the population is normally distributed and that the sample has been randomly selected. 10) In one town, monthly incomes for men with college degrees are found to have a standard deviation of $650. Use a 0.01 significance level to test the claim that for men wi
Use the traditional method to test the given hypothesis. Assume that the samples are independent and that they have been randomly selected 11) In a random sample of 500 people aged 20 24, 22% were smokers. In a random sample of 450 people aged 25 29, 14% were smokers. Test the claim that the proportion of smokers inthe two age
Use the given degree of confidence and sample data to find a confidence interval for the population standard deviation (sigma). Assume that the population has a normal distribution. 8) A sociologist develops a test to measure attitudes about public transportation, and 27 randomly selected subjects are given the test. Their m
1. Suppose a sample of n = 50 items is drawn from a population of manufactured products and the weight, X, of each item is recorded. Prior experience has shown that the weight has a probability distribution with m= 6 ounces and standard deviation= 2.5 ounces. Which of the following is true about the sampling distribution of
Independent measurements of a certain distance are identically distributed random variables with mean 20 and variance 3.5 ; how many measurements are necessary to ensure that the average of the measurements is accurate to within .2 of the mean with 97% accuracy. See the attached file.