Assume that your competitor's average sale price is 4000$ higher than your mean of the initial dataset (30 cars). Your claim is that your shops' prices, in general, are lower than your competitors' average. Set up a hypothesis test.

which direction would the null fall under?

A left-sided test: 0: = : <

A right sided test : 0: = : > c

. A two sided test: 0: = :