al APPLIED
2011-12-04 4:53 pm
Each weekday a man goes to work by bus .His arrival time at the bus stop is normally distributed with standard deviation 3 minutes.Hid mean arrival time is 8:30 am .Buses leave promptly every 5 minutes at 8:21 am,8:26 am ,etc.Find the probability that he catches the buuses at 8:36
回答 (1)
2011-12-04 5:09 pm
✔ 最佳答案
For the man to catch the bus at 8:36 am, he has to arrive the bus stop after 8:31 am but before 8:36 am.They are deviated from the mean arrival time by 1 min to 6 mins.
The bound of the test statistics, (difference between arrival time and mean) / standard deviation
So, P[(1/3 < z < 6/3)]
= P(1/3 < z < 2)
= P(0 < z < 2) - P(0 < z < 1/3)
From table
Prob = 0.4772 - 0.130567
Prob = 0.3466
參考: Prof. Physics
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