A 23-mile stretch of a two-lane highway east of Paso Robles, California, was once considered a “death trap” by residents of San Luis Obispo County. Formerly known as “Blood Alley,” Highway 46 gained notoriety for the number of fatalities (29) and crashes over a 240- week period. More than two-thirds involved head-on collisions. The file titled Crashes contains the simulated number of fatal crashes during this time period.
a. Determine the average number of crashes in the 240 weeks.
b. Calculate the probability that at least 19 crashes would occur over the 240-week period if the average number of crashes per week was as calculated in part a.
c. Calculate the probability that at least 19 crashes would occur over a five-year period if the average number of crashes per week was as calculated in part a.
d. A coalition of state, local, and private organizations devised a coordinated and innovative approach to dramatically reduce deaths and injuries on this road. During the 16 months before and after completion of the project, fatal crashes were reduced to zero. Calculate the probability that there would be no fatal crashes if the mean number of fatal crashes was not changed by the coalition. Does it appear that the aver-age number of fatal accidents has indeed decreased?