The number of wins in a season for 32 randomly selected professional football teams arelisted below. construct a 90% confidence interval for the true mean number of wins in a season. mean(x) = sum of 32 observations / 32 = 7.97 standard deviation( sd )=2.62 sample size(n)=32 confidence interval = [ 7.97 ± z a/2 ( 2.62/ sqrt ( 32) ) ] = [ 7.97 - 1.64 * (0.4632) , 7.97 + 1.64 * (0.4632) ] = [ 7.2,8.7 . what are the steps used to solve this? how did they find their standard deviation? also what does the z stand for in the confidence interval?