In: Statistics and Probability
The average daily volume of a computer stock in 2011 was mu equals35.1 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 28.9 million shares, with a standard deviation of sequals 11.2 million shares. Test the hypotheses by constructing a 95 % confidence interval. Complete parts (a) through (c) below. (a) State the hypotheses for the test.
Hypothesis: Vs
Since , the population standard deviation is unknown.
Therefore , use t-distribution.
df=degrees of freedom=n-1=40-1=39
Now , ; The Execl function is , =TINV(0.05,39)
Therefore , the 95% confidence interval is ,
Here , the value 35.1 does not lies in the confidence intervl.
Therefore , reject Ho.
Conclusion : Hence , the stock analyst believes that the stock volume in 2014 is different from the 2011 level.