Let x be a random variable representing dividend yield of Australian bank stocks. We may assume that x has a normal distribution with = 2.8%. A random sample of 16 Australian bank stocks has a sample mean dividend yield of 8.91%. For the entire Australian stock market, the mean dividend yield is = 6.4%.  If you wanted to test to determine if these data indicate that the dividend yield of all Australian bank stocks is higher than 6.4%, what is the value of the test statistic? Place your answer, rounded to 3 decimal places, in the blank. For example, 2.345 would be a legitimate entry