Blog

A study of new cars to predict city gas mileage (miles per gallon) from their weight (pounds) resulted in a correlation coefficient of r = –0.4 and an r2 = 0.16. Based on this information, which of the following statements is correct?

Use the boxplots to answer the next three questions. The boxplots below represent movie runtimes (the length of a movie in minutes) for a random sample of 100 movies in each of four major genres (drama, action, comedy, children’s). Put the genres in order of their IQRs from least to greatest.

Which of the following samples taken from the sample 7, 27, 43, 49, 52, 60 could be a bootstrap sample?

What is extrapolation and why is it a bad idea in regression analysis?

A random sample of records of home sales from March 1 to July 1, 2010 from the files maintained by the Charlottesville Board of Realtors gives the Price (in dollars) and Size (in square feet) of 32 homes.  The regression model is as follows: Predicted Price = 47,820 + [ 61 × (Size) ] In this context, does the y-intercept have a reasonable interpretation?

A dot plot of the speeds of a sample of 50 cars passing a policeman with a radar gun is shown below.   What proportion of motorists were driving above the posted speed limit of 65 miles per hour?

Male players at the high school, college, and professional ranks use regulation basketballs that weigh on average 22 ounces with a standard deviation of 1 ounce.  Assume that the weights of the basketballs are Normally distributed.  If a regulation basketball is randomly selected, what is the probability that it will weigh exactly 22.5 ounces?  Choose the best answer.

Norman is performing a hypothesis test in which he rejects the null hypothesis at a significance level of 0.05 because he obtains a p-value of 0.02.  Which of the following statements is true?

Use the following to answer the next three questions. A Division III men’s college basketball team is interested in identifying factors that impact the outcomes of their games.  They plan to use “point spread” (their score minus their opponent’s score) to quantify the outcome of each game this season; positive values indicate games that they won while negative values indicate games they lost.  They want to determine if “steal differential” (the number of steals they have in the game minus the number of steals their opponent had) is related to point spread.  The correlation between point spread and steal differential for the n = 25 games they played this season is r = 0.35.  Assuming that this season was a typical season for the team, they want to know if steal differential is positively correlated with point spread. State the hypotheses for testhing if this sample provides evidence that steal differential is positively correlated with point spread.

The width of the confidence interval for a single proportion gets narrower (i.e., smaller) when: