The mean gross annual income of certified tack welders are normally distributed with the mean of $20,000. the ship building association wishes to find out whether their tack welders earn more or less than $20,000 annually. they take a random sample of 81 tack welders and find a mean annual income of $20,200 and a standard deviation of $2,000. the alternate hypothesis is that the mean is not $20,000. conduct a hypothesis test at the 0.1 level of significance. a. state the null and alternate hypothesisb. state the level of significancec. compute the value of the test statisticd. determine the critical value and the decision rule, state your conclusion. e. pretend that the population standard deviation was known and the calculated test statistic was z = -2.05. find the p-value and state how significant the findings are.