Let x be a random variable representing dividend yield of Australian bank stocks. We may assume that x has a normal distribution with = 2.3%. A random sample of 18 Australian bank stocks has a sample mean of = 6.1%. For the entire Australian stock market, the mean dividend yield is = 5.5%. Do these data indicate that the dividend yield of all Australian bank stocks is higher than 5.5%? Use = 0.1. What is the value of the test statistic?