- #1
Saracen Rue
- 150
- 10
I don't really know how to explain it right off the bat, so I'm going to use an example first:
Say 2 coins are tossed. Let H1 = a head is tossed first and T2 = a tail is tossed second.
If you create an event space, you get {H1H2, H1T2, T1T2, T1H2}.
Therefore, the Pr(H1) must equal 1/2 and Pr(T2) = 1/2
Next, I want to attempt to find Pr(H1∩T2).
First, I need to find Pr(H1∪T2), which I'll do by using the formula Pr(A∪B) = n(A∪B)/n(universal set):
Pr(A∪B) = n(A∪B)/n(universal set)
Pr(A∪B) = 2+2/4
Pr(A∪B) = 4/4 = 1
However, there is a problem here as I can see by looking at the event space that this can't be true, as there's the event T1H2. So, my first question is why doesn't this work?
So, instead, I can find Pr(H1∩T2) just by looking at the even space, which ends up being 1/4. However, I don't know how I would find this without the event space. So, my second question is how would I find Pr(H1∩T2) by only using formulas (not looking at the even space).
Any help with this would be must appreciated as I honestly can't seem to understand probability at all.
Say 2 coins are tossed. Let H1 = a head is tossed first and T2 = a tail is tossed second.
If you create an event space, you get {H1H2, H1T2, T1T2, T1H2}.
Therefore, the Pr(H1) must equal 1/2 and Pr(T2) = 1/2
Next, I want to attempt to find Pr(H1∩T2).
First, I need to find Pr(H1∪T2), which I'll do by using the formula Pr(A∪B) = n(A∪B)/n(universal set):
Pr(A∪B) = n(A∪B)/n(universal set)
Pr(A∪B) = 2+2/4
Pr(A∪B) = 4/4 = 1
However, there is a problem here as I can see by looking at the event space that this can't be true, as there's the event T1H2. So, my first question is why doesn't this work?
So, instead, I can find Pr(H1∩T2) just by looking at the even space, which ends up being 1/4. However, I don't know how I would find this without the event space. So, my second question is how would I find Pr(H1∩T2) by only using formulas (not looking at the even space).
Any help with this would be must appreciated as I honestly can't seem to understand probability at all.