how do I determine one sided vs two sided t testing when int

how do I determine one sided vs two sided t testing when interpreting mileage data. Problem reads: The Consumer Safety Board is examining the advertising claims made by a car manufacturer regarding the significant improvements on the average miles without repairs (when driven on city roads and barring accidents) a newly introduced car model will run. The national average for this type of a car under these type of conditions is 58,030 miles.

Solution

Null hypothesis will defined to , the national average for this type of a car under these type of conditions is 58,030 miles. i.e U <58,030. In two tailed test we always define Null with equality condition. Here it defined to less than symbol and that tells it is one tailed test