A marketing company wishes to establish an estimate of the average salary for middle managers in the retail industry. Results of a random study on middle management salaries is contained below (also available for download here Salaries.xlsx). Construct a 90% confidence interval for the population mean. (3 Marks)

Sample of Middle Management Salaries in Retail Industry
83,700	84,200	82,400	84,700	71,700	74,000	40,100	71,600	70,400	62,700	78,100	88,300
61,600	60,300	88,600	69,700	55,600	53,800	77,100	59,900	58,600	57,000	70,200	57,500
52,500	40,600	45,900	81,100	41,100	88,800	88,500	64,900	53,400	74,800	47,800	63,200
76,300	84,500	70,400	46,600	73,600	81,400	78,500	73,600	47,600	69,800	86,500	63,700
62,700	81,300	56,600	88,100	41,700	77,300	69,400	55,200	52,300	87,300	52,400	88,300
53,700	86,900	78,400	49,800	55,000	49,000	88,300	54,700	87,400	60,500	45,400	50,600
71,500	49,600	50,900	45,200	69,900	66,300	51,700	71,700	49,300	40,800	43,200	88,900
45,400	63,200	65,600	47,400	49,100	60,800	61,200	88,500	52,300	59,500	47,900	77,300
43,700	48,800	89,300	75,100	53,000	59,400	58,600	86,900	87,000	71,800	67,000	53,100
71,500	49,400	74,400	66,400	55,100	44,700	71,600	51,700	40,900	68,500	73,400	67,000
89,300	62,600	71,900	49,500	54,600	47,400	51,400	84,600	70,700	50,800	65,700	89,600