1. James, a car enthusiast, conducted a study on the efficiency of cars. Fourteen cars from two different models of a car manufacturer are compared to see if the smaller model has a higher average MPG (miles per gallon) than the larger model. From this survey, the sample means and standard deviations of MPG are summarized below.

Smaller model

n = 7

mean = 28.2

standard deviation = 3.4

Larger model

n = 7

mean = 22.6

standard deviation = 4.0

Find the following:

• Ho and Ha
• significance level
• CV
• rejection and nonrejection region
• decision
• conclusion

2.) A researcher conducting an experiment in the lab predicted that an experimental treatment will produce a decrease in the population mean. The population has a mean of 45. For a 1-tailed test, what is the mean that the null hypothesis claims?