Questions from Business Statistics

Q: To measure progress in reading ability, students at an elementary school

To measure progress in reading ability, students at an elementary school take a reading comprehension test every year. Scores are measured in grade-level units; that is, a score of 4.2 means that a st...

Q: A researcher investigating the association between two variables collected some data and

A researcher investigating the association between two variables collected some data and was surprised when he calculated the correlation. He had expected to find a fairly strong association, yet the...

Q: A college admissions officer, defending the college use of SAT scores

A college admissions officer, defending the college use of SAT scores in the admissions process, produced the following graph. It shows the mean GPAs for last year freshmen, grouped by SAT scores. How...

Q: After keeping track of his heating expenses for several winters, a

After keeping track of his heating expenses for several winters, a homeowner believes he can estimate the monthly cost from the average daily Fahrenheit temperature by using the model Cost=133 2.13 Te...

Q: How does the speed at which you drive affect your fuel economy

How does the speed at which you drive affect your fuel economy? To find out, researchers drove a compact car for 200 miles at speeds ranging from 35 to 75 miles per hour. From their data, they created...

Q: Here are a plot and regression output showing the federal rate on

Here are a plot and regression output showing the federal rate on 3-month Treasury bills from 1950 to 1980, and a regression model fit to the relationship between the Rate (in %) and Years Since 1950...

Q: The graph shows the ages of both men and women at first

The graph shows the ages of both men and women at first marriage (www.census.gov). Clearly, the patterns for men and women are similar. But are the two lines getting closer together? Here are a timepl...

Q: In Exercise 41, you investigated the federal rate on 3-

In Exercise 41, you investigated the federal rate on 3-month Treasury bills between 1950 and 1980. The scatterplot below shows that the trend changed dramatically after 1980, so we computed a new regr...

Q: Has the trend of decreasing difference in age at first marriage seen

Has the trend of decreasing difference in age at first marriage seen in Exercise 42 gotten stronger recently? The scatterplot and residual plot for the data from 1980 through 2015, along with a regres...

Q: For humans, pregnancy lasts about 280 days. In other species

For humans, pregnancy lasts about 280 days. In other species of animals, the length of time from conception to birth varies. Is there any evidence that the gestation period is related to the animal li...