In order to estimate the difference between the average hourly wages of employees of two branches of a department store, the following data have been gathered. Downtown Store North Mall Store 25 20 Sample size Sample mean $9 $8 Sample standard deviation $2 $1 A 95% interval estimate for the difference between the two population means is 01.078 to 2.922 Ob 1.922 to 2.078 01.09 to 4.078 Od 0.078 to 1.922