I need help with this question.

5. (20 points) A company with a large fleet of cars hopes to keep gasoline costs down and sets a goal of attaining a fleet average of at least 26 miles per gallon. They check the gasoline usage for 50 company trips chosen at random, finding a mean of 25.02mpg and a standard deviation of 4.83mpg. Is this strong evidence that they have failed to attain their fuel economy goal? (a) State the appropriate hypotheses. (b) Describe the model we should use for inferences. Check all necessary conditions. (c) Test the above hypotheses using alpha-level = 0.05. (d) Find the confidence interval that is equivalent to the test in (c)