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Probability of Independent Events - Problem 1 4,764 views

Teacher/Instructor Carl Horowitz
Carl Horowitz

University of Michigan
Runs his own tutoring company

Carl taught upper-level math in several schools and currently runs his own tutoring company. He bets that no one can beat his love for intensive outdoor activities!

Finding the probability of independent events and independent events are basically events that can occur simultaneously having absolutely no bearing on each other.

What we're looking at now is a problem involving me an my brother. My brother was in a class of 20. I was in a class of 30 find the probability we were both valedictorians.

Now this is a little bit of a letter question because not everybody is always going to have a completely equal chance of being a valedictorian. I suck at English so therefore my chances are pretty much 0, but we're going to take that out of the equation and pretty much say that anybody has an equal chance of being a valedictorian.

So the probability of my brother being valedictorian, there are 20 students in his class, he is one of them so he just has a 1 out of 20 chance of being valedictorian, so here is 1 out of 20. What about me? Pretty much the same idea, there is one of me and I am coming out of a class of 30, so therefore I have a 1 out of 30 chance of being a valedictorian.

We are looking for both of these to occur so all we have to do is multiply these two things together and that will give us our answer, so we end up with one out of 600 chance.So independent events, you just look at it and say does this have an bearing on the other situation? The fact that my brother will be valedictorian and I'm not, they are independent, he's one student, I'm another student we're each going to have our our results.

So independent events you find the probability of each event, multiply them together.

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