After a group of (volunteer) experimental subjects achieved aspecified blood alcohol level from consuming liquor, psychologistsplaced each subject in a room and threatened them with electricshocks. Using special equipment, the psychologists recorded thestartle response time (in milliseconds) of each subject. The meanand standard deviation of the startle response times is 37.9milliseconds and 12.4 milliseconds, respectively.
a. Without knowing the shape of the distribution of theseresponse times, what is the interval that contains at least 75% ofresponse times?
b. If you are told that the shape of the distribution ofresponse times is normal,
i. What interval contains approximately 68% of startle responsetimes?
ii. What interval contains approximately 95% of startle responsetimes?
iii. What interval contains 99.7% (i.e., almost all) of startleresponse times?
iv. Approximately what percentage of startle response times fallbelow 25.5 milliseconds? HINT: Use the fact that a normaldistribution is symmetric around the mean to answer thisquestion.
