# Thread: how to solve this???

1. ## how to solve this???

An exam starts at t=0 & is supposed to be over at t=3.The students are asked to "wrap it up" at t=2.5.The relative number of students finishing an exam at time t is given in a graph(normalized).The function f(t) is approximated as:
f(t)=8/55 ,0<t<2.5
(204t-502)/55 ,2.5<t<3
-20t+62 , 3<t<3.1
Define outcomes and events.

-Im thinking that IF the outcomes are:8/55,(204t.....,-20...
Then would the events be only those at t=2.5???

2. ## Re: how to solve this???

This is a continuous distribution. probability at t=2.5 doesn't make sense. Only the probability at some interval make sense.

3. ## Re: how to solve this???

Originally Posted by vinux
This is a continuous distribution. probability at t=2.5 doesn't make sense. Only the probability at some interval make sense.
Yes. What f(t) is telling you is the probability of a student finishing between each time point.

4. ## Re: how to solve this???

can i say the events are: {0<t<2.5},{2.5<t<3},{3<t<3.1} ?

5. ## Re: how to solve this???

In continuous case you can define events in many ways.

You can take the following event

Probability that finishing exam within s time.

Here P(A_s) =F(s) same as the cumulative distribution function

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