Ms. stratton has 12 students in her pre-algebra class. on her desk she has a can with 12 popsicle sticks, one for each student in the class. each day, she chooses one popsicle stick at random. the student whose name is on the popsicle stick is assigned as the note-taker for class that day. if janey is a student in ms. stratton's pre algebra class, what is the probability that she is chosen today? write your answer as a decimal rounded to the nearest thousandth

the answer   is 200

step-by-step explanation:

this is a problem about poisson probabilities.   i don't know if you've

already studied poisson distributions, or if you have a place to look

to read more about the subject.  

here's how you can see a poisson distribution coming.   when there are

a lot of events that may happen at any time (or any place), and when

you're counting how many of them happen at a particular time (or a

particular place), and each event is independent of the others, then

the result is a poisson distribution.   this is roughly true for the

chocolate chips; one chip being in a cookie has only a small effect on

the probability that another chip will be in the cookie.

once you know you have a poisson distribution, you know a lot.   there

is only one parameter to a poisson distribution, so if you know the

mean, you know everything.   the form of the distribution is

  probability of n chips = {[e^(-x)]*(x^n)} / (n! )