Let X Be a Random Variable Representing Dividend Yield of Australian

Let x be a random variable representing dividend yield of Australian bank stocks. We may assume that x has a normal distribution with $\sigma$ = 2.3%. A random sample of 15 Australian bank stocks has a sample mean of x = 8.71%. For the entire Australian stock market, the mean dividend yield is $\mu$ = 5.5%. Do these data indicate that the dividend yield of all Australian bank stocks is higher than 5.5%? Use $\alpha$ = 0.05. What is the value of the test statistic?

A) -1.396
B) -0.360
C) 5.405
D) 0.360
E) -5.405