Posted by lashawn on .
Then, for the following two examples, determine the null and alternative as well as state which one represents the claim. State what type of test will be completed: lefttailed, righttailed, or twotailed.
The average score of the first exam for the class is an 81%.Claim 2: The average price for a gallon of gas is more than $3.00.

statistics 
PsyDAG,
It depends on what question you are asking.
Ho: mean = 81%
Ha: mean ≠ 81%
Twotailed
Ho: mean = $3.00
Ha: mean > $3.00
I'm not sure what you mean by righttailed or lefttailed. I don't use those specific terms. 
statistics (more) 
PsyDAG,
Upon further thought, righttailed may be the equivalent to positively skewed (deviant scores at higher values). If so, the second Ha would be righttailed.
The mean is influenced by deviant scores, like a fulcrum (balance point). Thus Ha for "more than $3.00" would be looking for a higher mean and "righttailed."