the school day consists of four block classes, each 90 mins long. Lunch is 30 mins. Passing time between classes and/or lunch is 5 mins.

1) if there is a fire drill at a random time during the day, what is the probability that is begins during lunch?
2) At a random time during a class, your teacher poses the "Question of the Day." If you are 10 mins late for class, what is the probability that you miss hearing the question?

Question

the school day consists of four block classes, each 90 mins long. Lunch is 30 mins. Passing time between classes and/or lunch is 5 mins.

1) if there is a fire drill at a random time during the day, what is the probability that is begins during lunch?
2) At a random time during a class, your teacher poses the "Question of the Day." If you are 10 mins late for class, what is the probability that you miss hearing the question?

anonymous · Answer

Total time of school is 5*4 + 90*4 + 30 = 410 mins.

lunch probability = 30/410 = 7.32%

question probability = 10/30 =33.3%. Assuming at any time in one class session.