Question

The average daily volume of a computer stock in 2011 was

muμequals=35.1

million​ shares, according to a reliable source. A stock analyst believes that the stock volume in 2014 is different from the 2011 level. Based on a random sample of

40

trading days in​ 2014, he finds the sample mean to be

30.2

million​ shares, with a standard deviation of

sequals=13.5

million shares. Test the hypotheses by constructing a

95​%

confidence interval. Complete parts​ (a) through​ (c) below.

Answer 1

The 95% confidence interval is (25.882, 34.518)

Since μ = 35.1 is outside the confidence interval, there is enough evidence to support the stock analyst's claim that the stock volume in 2014 is different from the 2011 level.