20 (1 point) To estimate , the mean salary of full professors at American colleges and universities, you obtain the salaries of a random sample of 400 full professors. The sample mean == is x = $73,220 and the sample standard deviation is s = $4400. Which of the following conditions is NOT required to construct a 90% confidence interval for ? O a random Ob 10ns N Oc np 10 and n(1-p) 210 Od n2 30 or stated as normal Time left for this assessment: 2001