The average daily volume of a computer stock in 2011 was million shares, according to a reliable source. A stock analyst believes that the stock volume in 2018 is different from the 2011 level. Based on a random sample of trading days in 2018, he finds the sample mean to be million shares, with a standard deviation of s million shares. Test the hypotheses by constructing a % confidence interval. Complete parts (a) through (c) below.