i need help

Suppose the incomes of all US hybrid automobile owners has a mean of $78,000 and a standard deviation of$8,300.Letting x bar be the mean income for 400 US hybrid automobile owners, a sampling distribution of x bar is formed.

a.What is the mean of x bar?_____________________

b.What is the standard deviation of x bar?______________

c.What is the shape of this sampling distribution of x bar?___________