measurements of the price of a stock during two independent sample periods yielded the following results: n1=5,n2=5;x1=8150,x2=7750;s1=25,s2=20
where n1,x1,s1 denote the sample size,sample mean,and sample standard deviation for the period i(=1,2),respectively . from experence,it is kown that the stock in question has a price which is normally distributed with the same variance in both sample periods. find a 99% confidence interval for the difference in mean stock price between the two sample periods