Suppose a pitcher claims that his pitch speed is less than 43 miles per hour, on average. Several of his teammates do not believe him, so the pitcher does a hypothesis test, at a 10% significance level, to persuade them. He throws 19 pitches. The mean speed of the sample pitches is 35 miles per hour. The pitcher knows from experience that the standard deviation for his pitch speed is 6 miles per hour.

• H0: 43; Ha: <43
• =0.1 (significance level)

What is the test statistic (z-score) of this one-mean hypothesis test, rounded to two decimal places?