Many states have attempted to reduce the blood- alcohol level at which a driver is declared to be legally drunk. There has been resistance to this change in the law by certain business groups who have argued that the current limit is adequate. A study was conducted to demonstrate the ­effect on reaction time of a blood- alcohol level of .1%, the current limit in many states. A random sample of 25 persons of legal driving age had their reaction times recorded in a standard laboratory test procedure before and after drinking a sufficient amount of alcohol to raise their blood alcohol to a .1% level. The difference (After - Before) in their reaction times in seconds was recorded as follows:

a. Graph the data and assess whether the population has a normal distribution.
b. Place a 99% confidence interval on both the mean and the median differences in reaction times of drivers who have a blood- alcohol level of .1%.
c. Is there sufficient evidence that a blood- alcohol level of .1% causes any increase in the mean reaction time?
d. Is there sufficient evidence that a blood- alcohol level of .1% causes any increase in the median reaction time?
e. Which summary of reaction time differences seems more appropriate, the mean or median? Justify your answer.

Transcribed Image Text:

01 0204 05 07 09 11 26 27 7 28 28 29 29 30 31 32 33 35 36 38 39 39 40