Do people who work for non-profit organizations differ from those who work at for-profit companies when it comes to personal job satisfaction? Separate random samples were collected by a polling agency to investigate the difference. Data collected from 422 employees at non-profit organizations revealed that 377 of them were "highly satisfied." From the for-profit companies, 431 out 518 employees reported the same level of satisfaction. Find the standard error of the difference in sample proportions.

A sports reporter suggests that professional baseball players must be, on average, older than professional football players, since football is a contact sport and players are more susceptible to concussions and serious injuries. Using data from sports.yahoo.com, one player was selected at random from each team in both professional baseball (MLB) and professional football (NFL). The data are summarized below.

$$\begin{array}{l|r|r} & \text { MLB } & \text { NFL } \\ \hline {n} & 30 & 32 \\ \overline{y} & 27.5 & 26.16 \\ {s} & 3.94 & 2.78 \end{array}$$

To perform inference on these two samples, what conditions must be met? Are they? Explain.

Researchers comparing the effectiveness of two pain medications randomly selected a group of patients who had been complaining of a certain kind of joint pain. They randomly divided these people into two group, then administered the pain killers. Of the 112 people in the group who received medication A, 84 said this pain reliever was effective. Of the 108 people in the other group, 66 reported that pain reliever B was effective.

Write a 95% confidence interval for the percent of people who may get relief from this kind of joint pain by using medication A. Interpret your interval.

Data collected in 2010 by the Behavioral Risk Factor Surveillance System revealed that in the state of New Jersey, 15.7% of whites and 15.9% of blacks were cigarette smokers. Suppose these proportions were based on samples of 2449 whites and 464 blacks. a) Create a 90% confidence interval for the difference in the percentage of smokers between black and white adults in New Jersey. b) Does this survey indicate a race-based difference in smoking among American adults? Explain, using your confidence interval to test an appropriate hypothesis. c) What alpha level did your test use?

In preparing a report on the economy, we need to estimate the percentage of businesses that plan to hire additional employees in the next 60 days. How many randomly selected employers must we contact in order to create an estimate in which we are 98% confident with a margin of error of 5%?

A man who moves to a new city sees that there are two routes he could take to work. A neighbor who has lived there a long time tells him Route A will average 5 minutes faster than Route B. The man decides to experiment. Each day, he flips a coin to determine which way to go, driving each route 20 days. He finds that Route A takes an average of 40 minutes, with standard deviation 3 minutes, and Route B takes an average of 43 minutes, with standard deviation 2 minutes. Histograms of travel times for the routes are roughly symmetric and show no outliers.

Find a 95% confidence interval for the difference in average commuting time for the two routes. (From technology, df = 33.1)

In the description of independent samples, four common methods were given for generating independent samples. In each case, give an example of a research question for which independent samples would be collected using the method described. Random samples are taken separately from two populations, and the same response variable is recorded for each individual. One random sample is taken, and a variable is recorded for each individual, but then units are categorized as belonging to one population or another, such as male and female. Participants are randomly assigned to one of two treatment conditions, such as diet or exercise, and the same response variable, such as weight loss, is recorded for each individual unit. Two random samples are taken from a population, and a separate variable is measured in each sample. Then the results are compared

Compare and contrast profit and nonprofit organizations?

The information in the earlier exercise was used to create a 95% two-proportion confidence interval for the difference between Canadians and U.S. citizens who were born in foreign countries. Interpret this interval with a sentence in context.

95% confidence interval for

$$P_\text{Canadians} - P_\text{Americans}\ \text{is} (3.24\%, 9.56\%)$$

A random work sample of operators taken over a 160hour work month at Tele-Marketing, Inc., has produced the following results. What is the percentage of time spent working?

Which of the following correlation coefficients represents the strongest relationship between two variables? a. +0.30 b. +0.75 c. +1.3 d. -0.85 e. -0.05

For each of the following settings, define the parameter of interest and write the appropriate null and alternative hypotheses for the test that is described. According to the Humane Society, 47% of U.S. households own at least 1 dog. You suspect that the proportion of households that own at least one dog among students at your school is higher than the national proportion.

determine the test statistic, H.

$$\begin{matrix} \text{X} & \text{Y} & \text{Z}\\ \text{7} & \text{9} & \text{4}\\ \text{4} & \text{4} & \text{5}\\ \text{3} & \text{8} & \text{10}\\ \text{ } & \text{3} & \text{7}\\ \end{matrix}$$

Suppose an advocacy organization surveys 960 Canadians and 192 of them reported being born in another country (www.unitednorthamerica.org/simdiff.htm). Similarly, 170 out of 1250 Americans reported being foreign-born. Find the standard error of the difference in sample proportions.