Daniella N.

asked • 09/30/15

statistics help

The number of fatal car crashes per day in Houston is shown in the table below. Let X be the random variable representing the number of fatal crashes. Find P(X < 2). Hint: convert the table to a probability distribution first by dividing the "Days" column by the total numberof days.

Number of Fatal Crashes
0
1
2
3
4
5

Number of Days
144
172
128
37
7
1

2 Answers By Expert Tutors

By:

Brian A. answered • 10/01/15

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5 (7)

Former Math professor and CFA Charterholder for Math and Finance Tutor

Maurizio T.

tutor
Good point, Brian! The Poisson is a non-very-well understood "creature"....
It would surely be a better description of the problem at hand.  Maybe a student would be appreciated if he/she followed your hint.
Some instructors do not even bother to check if their take-home tests have solutions on the internet, so I doubt that
they would care if one just follow the simplistic approach implicit in the question or your much more correct interpretation.
 
One student at a local community college told me that his calculus "professor" (yes, tenured too) who just has a master's degree told the class "I have a master's degree and i did not go for a ph.d. because it is essentially not very useful!" Maybe so, but are you suppose to tell that to students who are paying to earn a degree!?  
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10/01/15

Brian A.

Yep, and if you caught him at a weak moment he would say that he would cut off his hand to be able to write Ph.D. after his name. 
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10/01/15

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