If a chef claims that her meatball weight is not equal to 4 ounces, on average. Several of her customers do not believe her, so the chef decides to do a hypothesis test, at a 10%significance level, to persuade them. She cooks 13 meatballs. The mean weight of the sample meatballs is 3.9 ounces. The chef knows from experience that the standard deviation for her meatball weight is 0.6 ounces.

• H0: =4; Ha: 4
• =0.1 (significance level)

How would you figure out what the the test statistic (z-score) of this one-mean hypothesis test, rounded to two decimal places?