A 90% confidence interval for the average salary of all CEOs in the electronics industry was constructed using the results of a random survey of 45 CEOS. The interval was ($110,389, $128,192). Give a practical interpretation of the interval. A B C D We are 90% confident that the mean salary of the sampled CEOs falls in the interval $110,389 to $128,192. 90% of the sampled CEOs have salaries that fell in the interval $110,389 to $128,192. 90% of all CEOs in the electronics industry have salaries that fall between $110,389 to $128,192. We are 90% confident that the mean salary of all CEOs in the electronics industry falls in the interval $110,389 to $128,192.

Two popular brands of tires for tractor-trailers are the Puma and the Eternal. Salma is a buyer for a major shipping company and wants to determine if there is any difference between the two brands of tire in the mean distance (in thousands of km) driven on them before they need to be replaced. In the company's testing lab, Salma tests a random sample of 14 Puma tires and a random sample of 15 Eternal tires. (These samples are chosen independently.) For the Puma tires, the sample mean distance (in thousands of km) until they would need to be replaced is 54.71 with a sample variance of 5.95. For the Eternal tires, the sample mean distance (in km) until they would need to be replaced is 50.21 with a sample variance of 37.75. Assume that the two populations of distances driven are approximately normally distributed. Can Salma conclude, at the 0.05 level of significance, that there is a difference between the population mean of the distances (in thousands of km) driven on Puma tires before…

An arborist is interested in determining the mean diameter (in centimeters) of mature white oak trees at a certain height above the base. She measures 7 of these trees and finds the following sample statistics: F = 49.09 and s = interval for the mean diameter of a mature white oak tree. 13.80. Construct a 95% confidence

Use the Excel output to write out the conclusions of the Two-way Anova F-test, and use a 5% significance level. Choose the options that will create the correct interaction conclusion. The interaction P-value of                             [ Select ]                          ["0.0000037773", "0.00000033314", "0.11225061"]            is                             [ Select ]                          ["low", "not very low"]            , so we                             [ Select ]                          ["cannot conclude", "conclude"]            that there is significant interaction between the two categorical variables.

The mean number of sick days an employee takes per year is believed to be about 10. Members of a personnel department do not believe this figure. They randomly survey 8 employees. The number of sick days they took for the past year are as follows: 10; 5; 13; 3; 11; 8; 6; 9. Let X = the number of sick days they took for the past year. Should the personnel team believe that the mean number is about 10? Conduct a hypothesis test at the 5% level.Note: If you are using a Student's t-distribution for the problem, you may assume that the underlying population is normally distributed. (In general, you must first prove that assumption, though.) What is the test statistic? (If using the z distribution round your answers to two decimal places, and if using the t distribution round your answers to three decimal places.)   t  =    Construct a 95% confidence interval for the true mean. Sketch the graph of the situation. Label the point estimate and the lower and upper bounds of the confidence…

The principal randomly selected six students to take an aptitude test. Their scores were:88.0 84.1 74.9 83.2 83.7 85.5Determine a 90% confidence interval for the mean score for all students.

A graduate student is interested in how viewing different types of scenes affects working memory. For his study, he selects a random sample of 36 adults. The subjects complete a series of working memory tests before and after walking in an urban setting. Before the walk, the mean score on the test of working memory was 9.1. After the walk, the mean score was 1.4 higher. The graduate student has no presupposed assumptions about how viewing different types of scenes affects working memory, so he formulates the null and alternative hypotheses as: H00 : μDD = 0 H11 : μDD ≠ 0 Assume that the data satisfy all of the required assumptions for a repeated-measures t test. The graduate student calculates the following statistics for his hypothesis test: Mean difference (MDD) 1.4 Estimated population standard deviation of the differences (s) 1.6 Estimated standard error of the mean differences (sMDMD) 0.2667 Degrees of freedom (df) 35 The t statistic 5.25 The critical values of t…

Students in an experimental psychology class did research on depression as a sign of stress. A test was administered to a sample of 30 students. The scores are given. Complete parts (a) through (c) below. 32 54 11 15 35 21 OA. 158 34 15 55 51 11 35 2 1457 3 1234567 4123445566 511245666 34 33 46 OB. 11155 (a) Find the mean and median of the data. The mean is . (Round to three decimal places as needed.) 44 26 27 The median is .(Type an integer or a decimal.) (b) Draw a stem-and-leaf plot for the data using one row per stem. Which stem-and-leaf plot below shows the data? 2 112677 3 233445556 4 244666 5 1456 ... 21 42 38 OA. The distribution is symmetric. B. The distribution is skewed right (positively skewed). OC. The distribution is skewed left (negatively skewed). O D. The distribution is uniform. (c) Describe the shape of the distribution. Which description below best describes the shape of the distribution? 56 46 OC. 1112455668 2 14556 3 15 4 13457 5 223446667 46 27 33 35 22 44 36 0…

From candy to jewelry to flowers, the average consumer was expected to spend $104.63 for Mother’s Day in 2005, according to a Democrat & Chronicle article. Local merchants thought this average was too high for their area.  They contracted an agency to conduct a study. A random sample of 60 consumers was taken at a local shopping mall the Saturday before Mother’s Day and produced the sample mean amount of $94.27.  If σ = $29.50, does the sample provide sufficient evidence to support the merchants’ claim at the 0.03 level of significance? 1. Do you recognize any flaws in this study and what conclusions can you draw?     The article “Well-fed Crickets Bowl Maidens Over” reports that female field crickets are attracted to males that have high chirp rates and hypothesized that chirp rate is related to nutritional status. The usual chirp rate doe male field crickets was reported to vary around a mean of 60 chirps per second. To investigate whether chirp rate was related to nutritional…

The following box plot represents a sample of house prices. House prices ($1000s) 160 Find and interpret the first quartile Q1. 155 Ex: 19000 150 Pick 145 Pick 25% of the house prices fall above Q1. Find al 25% of the house prices fall below Q1. Q1 is the median value. 140 135 Pick 130 125 120