The average daily volume of a computer stock in 2011 was μ=35.1 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 40 trading days in​ 2018, he finds the sample mean to be 31.8 million​ shares, with a standard deviation of s=14.6 million shares. Test the hypotheses by constructing a 95​% confidence interval. ​(a) State the hypotheses for the test.
(b) Determine if the researcher will reject the null hypothesis.