Exam 5: Statistical Reasoning

Solve the problem. -For the study described below, identify the sample statistic. A manufacturer of light bulbs wants to determine the average lifetime of its 75 -watt light bulbs. Among 120 randomly selected 75 -watt light bulbs, the average lifetime was 1007 hours.

State whether you think that the variables have strong positive correlation, weak positive correlation, strong negativecorrelation, weak negative correlation, or no correlation. -Hours of exercise per week and blood pressure.

In order to answer the given question, which of the following types of study would be the most appropriate: anexperiment without blinding, an experiment with single blinding, an experiment with double blinding, an observationalstudy, or a case-control study? -Are short women more likely to develop breast cancer than tall women?

Make a bar graph to represent the data. -The following table shows the number of female infants born at Hospital X on New Year's Day (Jan. 1). Create a vertical bar graph. No. of Female Year Infants Born Jan 1 1970 21 1971 12 1972 18 1973 30 1974 27 1975 24

Describe how you would apply the five basic steps of a statistical study to the given issue. -You want to know the percentage of college seniors who regret their choice of major.

A statement is made about correlation. State whether the correlation is positive or negative and whether the correlation ismost likely due to coincidence, a common underlying cause, or a direct cause. -People who eat a lot of junk food are heavier, on the whole, than those who do not.

Identify which of these types of sampling is used: simple random, stratified, systematic, or convenience. -The name of each contestant is written on a separate card, the cards are placed in a bag, and three names are picked from the bag.

Answer as requested. -Suppose that there is perfect positive correlation between the number of hours studied for a test and score on the test. Which of the following statements must be true? More than one statement May be true. A: If we know the number of hours a given student studied, we will be able to perfectly predict Their test score. B: If Anne studied twice as long as Manuel, she will score twice as much. C: If Lu Yi studied ten hours more than Andrea, Lu Yi will score ten points more than Andrea. D: All data points lie perfectly on a horizontal line.

State whether the scatter diagram shows strong positive correlation, weak positive correlation, strong negativecorrelation, weak negative correlation, or no correlation. -

Identify the variable as either qualitative or quantitative. -The movie critics' ratings of the new movie on a scale of $0 - 10$ where $10 =$ the best movie ever seen and $0 =$ the worst movie ever seen

Solve the problem. -For the study described below, identify the sample statistic. 1500 American women working for large companies were polled to determine the percentage that Felt that women were under represented in management positions in their company.

Choose the best wording for the question in the study. -Proposition EZ proposes to raise the state sales tax by one quarter of a percent. The proceeds will be earmarked for music education in the public schools. If you want to determine whether or not it Will pass, which of the following survey questions will give you the most accurate results?

Use the guidelines to evaluate the study. From the information given, what is the biggest flaw in the study? -A medical researcher randomly selects 500 Japanese people and 500 Americans. She questions the 1000 people. She finds that the Americans work longer hours on average and also that the Americans have a higher rate of heart disease. She concludes that working longer hours is Associated with a higher incidence of heart disease.

Construct a line chart for the data. -The table shows the price of a volatile stock from the months January through December of the same year as determined by the closing price on the last trading day of the month. The price is Rounded to the nearest dollar. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 32 70 73 111 184 87 45 42 67 87 94 111 Construct a time series line chart for the data.

Use the guidelines to evaluate the study. From the information given, what is the biggest flaw in the study? -A pharmaceutical company conducted a study to test the effectiveness of its new anti-depression medication. 500 adults suffering from depression were selected at random and were randomly Assigned to either a treatment group or a placebo group. The experiment was double blind. The Results were analyzed by the company.

Answer the question. -The bar graph below shows the average cost of renting a studio in a certain city in each of the years 1994 through 1998. By what percentage does the average rental price increase from 1994 to 1995? Obtain a truncated version of the graph by sliding a piece of paper over the bottom portion of the graph so that the scale on the vertical axis starts at 300. In the truncated graph, by what percentage does the price appear to increase from 1994 to 1995? Why is the truncated graph misleading?

The graph below shows estimated world population for the period $4000 \mathrm { BC } - 2000 \mathrm { AD }$ . Note that the logarithm of the world population and not actual population is plotted on the vertical axis. This means, for example, that when the graph reaches 7 on the vertical scale, world population is $10 ^ { 7 }$ and when the graph reaches 9 on the vertical scale, world population is $10 ^ { 9 }$ . Use the graph to answer the question. -How does world population in the year 1000 AD compare with world population in the year 2000 BC?

Use the graph to answer the question. -The following chart shows the percentage of cigarette smokers in Gotham City. In which year does the percentage of men who smoke exceed the percentage of women who smoke by roughly 9 percentage points.

Make a scatter diagram for the data. -The table shows the life expectancy at birth for females and per capita GDP for nine countries. (Data for 1995) Country Life Expectancy at birth (female) Per Capita GDP (dollars) Afghanistan 45 200 Chile 78 7000 Ghana 58 1500 Guatemala 68 3000 Kenya 54 1200 Spain 81 12,700 Thailand 72 5500 New Zealand 80 15,700 United States 80 24,700 Plot per capita GDP on the horizontal axis and life expectancy on the vertical axis.

Describe how you would apply the five basic steps of a statistical study to the given issue. -As a marketing executive for a computer company you wish to determine the average length of time that owners of personal computers in the U.S. keep a computer before buying a newer model.