A research firm tracks the average home ghway speed of 30 drivers driving home on Day one. For the next 10 days, the drivers are given two cups of...

A research firm tracks the average home ghway speed of 30 drivers driving home on Day one. For the next 10 days, the drivers are given two cups of coffee 1 hour before the drive home. On the 10th day the average has ghway speed is measured again. Does this study involve dependent or independent samples? You are interested in knowing if there is a statistical difference in driving speeds between Day 1 and Day 10.