n = number of samples = 40
= standard deviation = $9,500
= mean = $44,000
90% confidence interval = [ - 1.645/n, + 1.645/n]
the number 1.645 from the above equation is looked up in a table or in a calculator I can show you how to do this if you need it.
Therefore the interval is 44,000 plus or minus (1.645*9,500/40) somewhow I am not getting an answer in your list . . . can anyone help?