It is claimed that the average salary for managers in a particular company is $54000. The standard deviation of that salary is known to be $2000. A sample of 100 managers is selected and a sample mean of $56000 is derived. If the goal is to test whether the average salary for managers is greater than $54000 what is the value of the critical test statistic at the 10% level of significance?a. z = 1.280b. z = 1.645c. t = 1.290d. t = 1.660