Exam 10: Inference About Means and Proportions With Two Populations

The following table shows the monthly sales (in units) of six salespersons before and after a bonus plan was introduced.Using α = .05, determine whether the bonus plan has increased sales significantly.Assume the population of differences is normally distributed.(For the following matched samples, let the difference d = After - Before.)

The results of a recent poll on the preference of voters regarding presidential candidates are shown below. ​ Using α = .05, test to determine whether or not there is a significant difference between the preferences for the two candidates.

Two major automobile manufacturers have produced compact cars with engines of the same size.We are interested in determining whether or not there is a significant difference in the mean MPG (miles per gallon) when testing for the fuel efficiency of these two brands of automobiles.A random sample of eight cars from each manufacturer is selected, and eight drivers are selected to drive each automobile for a specified distance.The following data (in miles per gallon) show the results of the test.Assume the population of differences is normally distributed. ​ At α = .10, the null hypothesis

The management of a department store is interested in estimating the difference between the mean credit purchases of customers using the store's credit card versus those customers using a national major credit card.You are given the following information. ​ At 95% confidence, the margin of error is

When each data value in one sample is matched with a corresponding data value in another sample, the samples are known as _____ samples.