A car manufacturer believes electric cars will result in greater yearly savings for customers. His company designed an electric model version of their best-selling SUV and wants to compare the maintenance costs of the electric model vs. the original gas model. The usual mean for the gas-powered vehicle is =112 dollars per month and a standard deviation of =27. Tests are conducted on a sample of n = 36 electric cars. The sample mean ends up being M= 103 dollars per month.

1. State the study hypotheses (using sentences or annotations) (4 pts)

1. Using a two-tailed test with = .05, is the data sufficient to conclude that electric cars result in greater monetary savings than gas-powered vehicles? In your answer, state (1) the boundaries of the critical region, (2) the test statistic for your sample, and, (3) your decision. (6 pts)

1. Compute Cohen's d for this study (2 pts)

1. What if the researcher had used a two-tailed test with = .01? In your answer, state (1) the boundaries of the critical region, (2) your decision. (2 pts)

1. What if the researcher had predicted that electric vehicles would cause an increase in maintenance costs and decided to use a one-tailed test with = .05? In your answer, state (1) the boundary of the critical region, (2) your decision. (2pts)

1. What if the researcher had predicted that electric vehicles would cause adecrease in maintenance costs and decided to use a one-tailed test with = .01? In your answer, state (1) the boundary of the critical region, (2) your decision. (2 pts)