Compute the 90% confidence interval for population mean.
At the end of 1990 and 1991 and 1992 the average prices of a share of stock in a money market portfolio were $34.83, $34.65 and $31.26 respectively. To examine the average share price at the end of 1993, a random sample of 30 stocks was drawn and their closing prices on the last trading day of 1993 were observed with a mean of 33.583 and a standard deviation of 19.149. Appraisal the average price of a share of stock in the portfolio at the end of 1993 with a 90% confidence interval.
A. [27.643 39.523]
B. [32.360 34.650]
C. [33.583 34.651]
D. [26.433 40.733]
E. [26.731 40.435]