Paired or two sample

An experiment is conducted on the effect of alcohol on perceptual-motor ability. Ten subjects are each tested twice, once after having two drinks and once after having two glasses of water. The two tests were on two different days to give the alcohol a chance to wear off. Half of the subjects were given alcohol first and half were given water first. The scores of the 10 subjects are shown below. The first number for each subject is their performance in the "water" condition. Higher scores reflect better performance. Test to see if alcohol had a significant effect. Use 0.01 significance level!

Water Alcohol Difference 16 13 15 13 1 1 20 OWOWWNN-NW 14 Average 15.3 13.4 1.9 Sample std. dev. 2.67 2.95 1.20