Based on data covering two consecutive school years, the National Safety Council found that fourth to sixth graders engaging in unorganized activities on school grounds experienced injuries at the rate of 2.4 injuries per 100 thousand student-days.
On the average, how many student-days elapse between injuries to fourth to sixth graders in unorganized activities at school, and what is the probability that the next such injury will occur before 45 thousand student-days have passed?