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probability

by apple100 » Thu Apr 16, 2009 4:10 pm
What is the probability that event E or event F or both will occur?

1) probability that E will occur is 0.6
2) probability that F will occur is 0.4.



[spoiler]OA: E[/spoiler]
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by scoobydooby » Thu Apr 16, 2009 9:35 pm
probability that event E or event F or both will occur=>probability atleast 1 of them will occur: p(EUF)=p(E)+p(F)-P(F and E)

1) gives only p(E). not. sufficient.

2) gives only p(F). not sufficient

together, we do not have P(F and E). so both together not sufficien

E
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by apple100 » Thu Apr 16, 2009 9:39 pm
scoobydooby wrote:probability that event E or event F or both will occur=>probability atleast 1 of them will occur: p(EUF)=p(E)+p(F)-P(F and E)

1) gives only p(E). not. sufficient.

2) gives only p(F). not sufficient

together, we do not have P(F and E). so both together not sufficien

E
is P(F&E) not equal to P(E) * P(F)?
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by scoobydooby » Thu Apr 16, 2009 9:43 pm
P(F&E) = P(E) * P(F) only when E and F are independent events, ie the out come of one event is not dependent on the outcome of the other.

also, we do not know if E and F are mutually exclusive events, ie they cant occur together, so cant say P(F &E)=0
Last edited by scoobydooby on Thu Apr 16, 2009 9:49 pm, edited 1 time in total.
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by apple100 » Thu Apr 16, 2009 9:45 pm
scoobydooby wrote:P(F&E) = P(E) * P(F) only when E and F are independent events, ie the out come of one event is not dependent on the outcome of the other.
and in this case, we do not know whether the events are independent or not, correct?
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by scoobydooby » Thu Apr 16, 2009 9:50 pm
apple100 wrote:
scoobydooby wrote:P(F&E) = P(E) * P(F) only when E and F are independent events, ie the out come of one event is not dependent on the outcome of the other.
and in this case, we do not know whether the events are independent or not, correct?
yes, thats right. no information on the nature of the events.
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