Let x be a random variable representing dividend yield of bank stocks. we may assume that x has a normal distribution with σ = 2.6%. a random sample of 10 bank stocks gave the following yields (in percents). 5.7 4.8 6.0 4.9 4.0 3.4 6.5 7.1 5.3 6.1 the sample mean is x bar = 5.38%. suppose that for the entire stock market, the mean dividend yield is μ = 4.2%. do these data indicate that the dividend yield of all bank stocks is higher than 4.2%? use α = 0.01.